For an entire 153 episodes (the original DragonBall TV series), we don't even know that we're watching a member of the Saiyan race! We first discover that Goku is indeed a Saiyan with the arrival of Raditz, Goku's older brother. Raditz explains that Goku is one of four remaining Saiyans (Goku, Raditz, Nappa, and Vegeta). The "Saiya" are a fighting race that eventually took over their home planet ("Planet Vegeta") from the technologically advanced but physically weak Tsufuru race. The Saiyans were later employed by Freeza to take over planets, exterminating any life forms on them. Hired mercenaries, you could call them.

In their "regular" state, a Saiyan is characterized by black hair and a desire to fight, fight, fight! They appear to be human, with possibly the only telling factor being their tail. However, at a certain point, a Saiyan's hair stops growing; playing into this, at yet another undetermined point, the tail will stop re-growing if removed.

It seems, though, that Saiyans can cut their hair and have it regrow; it simply will not exceed a certain length. Half-breeds (or less, as seen later on) do not seem to have this same feature of the hair; their hair is not necessarily black, either (as seen with Trunks).

Every Saiyan has the ability to transform (especially Ôzaru), but this does not necessarily mean that they all transform at all, never mind to all stages!

Goku is the first to go through the transformation into a Super Saiyan. It is widely speculated that the Sentô Ryoku ("combat strength," or if you must, "power level") of the character must be around 180,000, which Goku reaches on Namek; this cannot be confirmed or denied, however (it's merely speculation). The transformation into a Super Saiyan is generally caused by an overwhelming sense of rage and hatred.

In Goku's case, when Freeza shoots Piccolo through the chest (nearly killing him), murders Kuririn by causing him to explode from the inside, and declares he will be going after Gohan next... well... yeah, that just about does it.

The stage is characterized by giant spikey golden hair. The pupils also turn a bluish green color. The power of the character is exponentially increased. Control over this power, however, is not always the easiest thing at first. The Super Saiyan stage has an interesting effect on the Son family, in addition to its normal effects: the way their eyes are drawn changes slightly. Normally, the outline around the eye is not fully drawn (it circles around about 3/4 of the way the eyeball). When in Super Saiyan, their eyes are fully surrounded by an outline (the same way that all villains are drawn; this is due to Toriyama wanting to show the anger and hatred that must be present for a Super Saiyan transformation).

The Super Saiyan transformations of the two children, Goten and Trunks, come under great debate. Goten and Trunks were able to transform around the same time; Goten at 7 years of age, and Trunks at 8 years of age. Many people believe that Goku and Vegeta passed on a different kind of DNA to these children, since both of them had achieved SSJ by the time of conception. Perhaps their tail removal, at birth, also had some kind of play in unleashing their dormant power ahead of other characters (who did not have their tails removed until much later). Regardless, their feats remain amazing to all.

CHARACTER	NOTES
Goku	DBZ Episode 95; Manga Chapter 317 Freeza's attempt to kill Piccolo, murder of Kuririn, and threats of going after Gohan next, were more than enough to set off Goku's transformation into a Super Saiyan, the first in the series.
Trunks (Future)	DBZ Episode 120; Manga Chapter 331 DBZ TV Special 2; Manga Chapter "Trunks - The Story" The first time we see Trunks transform into a Super Saiyan is during his challenging of Freeza. By this point, however, Trunks has perfected his transformation. The original cause, however, was Gohan's death (by the Jinzôningen) in his future timeline. Note that in the special manga chapter, Trunks is already able to transform into SSJ when Gohan is killed.
Vegeta	DBZ Episode 129, Manga Chapter 343 Another character whose first transformation is not actually his first! Vegeta returns to the battlefield to defeat Jinzôningen #19 for Goku, whose heart disease is affecting him. Vegeta transforms into a Super Saiyan, astounding everyone. However, his first transformation was actually while out training in Goku's absence. The fact that Goku had surpassed him, and the anger at himself for not being able to accomplish the same, nearly ate him alive, bringing his transformation into a Super Saiyan.
Gohan	DBZ Episode 160, Manga Chapter 382 Discovering that a half-Saiyan can reach SSJ (as seen with Trunks), Goku pushes his son to his limits while training in the Room of Spirit and Time. While trying to repel one of his father's attacks, Gohan becomes so frustrated by his weakness and inability to protect his friends that he finally transforms into a Super Saiyan.
Goten	DBZ Episode 206, Manga Chapter 427 The original reason for Goten's transformation is unknown, but when he shows his mother that he is able to transform into a Super Saiyan, she is not very happy... !
Trunks (Chibi)	DBZ Episode 207, Manga Chapter 429 The original reason for Chibi Trunks's transformation is unknown, but when Vegeta finds out, he wonders if there's a "Super Saiyan Bargain Sale" going on!
Gotenks (Goten + Trunks)	DBZ Episode 253, Manga Chapter 482 Goten and Trunks were individually already able to reach Super Saiyan, and the fusion of the two proved no different.
Vegetto (Goku + Vegeta)	DBZ Episode 269, Manga Chapter 504 Goku and Vegeta were both well above Super Saiyan in strength, and the fusion of the two proved no different. Although the two fused while in their normal states, Vegetto turns into Super Saiyan with no problem. The second daizenshuu notes that Vegetto, as a Super Saiyan, has a power greater than that of a Super Saiyan 3.
Gogeta (Goku + Vegeta)	DBZ Movie 12 When Goku and Vegeta finally perform the Fusion Dance correctly to form Gogeta, he appears immediately in SSJ.
Broli	DBZ Movies 8, 10, 11 While he spends most of his fighting time in DBZ movie 8 in his "Legendary" form (see below), Broli starts out in regular Super Saiyan form (with the strange blue/green hair), and later fighting against the kids and Gohan in DBZ movie 10 before he uses the "Legendary" form again.
Bardock	Episode of Bardock More than twenty years later after his original debut, Naho Ooishi's spin-off manga, "Episode of Bardock", sees the character transform into a Super Saiyan during his battle in the past against Chilled.
THEORIES — CELL's CELLS
Cell	The Evidence... Since Cell is comprised from the cells of warriors including Goku and Vegeta, he is indeed partially Saiyan, at least in terms of "blood." Many times we see Cell "power-up" with the golden aura attributed with going Super Saiyan. Does he actually attain this level? It makes sense, but ultimately, it's left up to the reader/viewer to decide...! For more information, check out Cell's own transformations page.
THEORIES — DBGT CONTINUITY PROBLEMS
Pan Goku Jr. Vegeta Jr.	DBGT TV Special; DBGT Episode 64 Daizenshuu # 7 states that Pan cannot go SSJ due to the Saiyan blood in her being too diluted. However, we blatantly see both Goku Jr. and Vegeta Jr. able to go SSJ (almost with no problem) in the end of DBGT. The daizenshuu was written long before GT was nearing this part of the series; they had no way of knowing just what direction the show would take. GT's showing Goku Jr. and Vegeta Jr. going SSJ kills off the "diluted" blood theory, but still does not answer if Pan ever could / ever did go SSJ (especially in that "100 years" time between events in the last DBGT episode).

The first note to make would be that "USSJ" is nothing more than a fan term. However, it's extremely convenient to type out, so for this reason we will use it as an abbreviation. The actual Japanese wording is explained shortly below.

For a bit of extra history, the phrase "USSJ" was coined by a man named Curtis Hoffman in 1993. Back before FUNimation even owned the license to distribute the series in North America, Hoffman (just a fan of the series looking to share his love) wrote out extensive summaries of the DB tankôbon and even DBGT episodes as they aired in Japan. In the introduction to these summaries, Hoffman would list new characters and forms that make their first appearance. In order to differentiate forms that may not have an official name yet (not being named by characters, and there not yet being any official information guides), Hoffman decided to name the power-ups within the standard SSJ stage as "Ultra Saiya-jin". As Hoffman shared his summaries on his own website (Three Steps Over The Edge) and then later as a part of the website toriyama.org, these types of phrases became slightly adapted and treated as standard verbiage among English-speaking fans. This naming convention has obviously held true to this very day.

There are actually two stages within the "USSJ" stage, really just varying levels of the same exact thing. In the first stage, the muscles increase in size, while power rises. In the second stage, the muscles increase in size even more, the power rises even more, speed falls, and with some characters, the pupils disappear. In each of the those stages, more energy is consumed, as well. Three characters reach these stages; you'll find special information, by character, a little further down.

The USSJ stages (two of them) would each be considered, as Goku puts it in the original Japanese dialogue, "ichi-dankai no henshin" ("transformations of the first stage"). However, these two USSJ stages are thought of by Vegeta and Trunks as "Sûpâ Saiya-jin dai ni-dankai" and "Sûpâ Saiya-jin dai san-dankai" ("stage 2 / stage 3 of Super Saiyan," with "ni" and "san" meaning "two" and "three," respectively) Technically, these descriptions would probably better fit the actual SSJ2 and SSJ3, but we'll use them here as Vegeta & Trunks would.

Throw in some phrases that are only used a couple times in the series, together with some numbers... and you've got some confusion going on! Let's take it character by character, and see exactly how it all goes down.

VEGETA

Vegeta is the first character to show off a stage that exceeds the power of the normal Super Saiyan. Vegeta's original intent in training in the Room of Spirit and Time was not only to surpass Goku's power, but to also surpass the limitations of Super Saiyan... and in a way, he did so. In this stage, Vegeta's body mass increases greatly (creating an almost awkward looking character; so short, yet so buff!). Vegeta only showcases the first level of USSJ, which Trunks notes that Vegeta achieved in the first two months of training.

While training with Trunks in the Room of Spirit and Time, he seems to be completely unaware that Trunks is able to surpass him (as seen by Trunks hiding this stage until Vegeta is unconscious). How he was able to MISS it during the training will remain a mystery forever! Interestingly, it would seem that Vegeta may have been able to reach USSJ2, himself. Mysteriously, after conceding to Cell, Trunks notes, "So that's why dad chose not to transform this way... He knew this would happen...." So did Vegeta actually reach USSJ2? He certainly never showed it to us, if he did!

(FUTURE) TRUNKS

While obvious that Trunks is able to reach USSJ1, he takes it one step further to USSJ2 (note: this is not SSJ2, which is explained below. Trunks never reaches SSJ2). His body mass increases along with his raw power, but his speed unfortunately decreases, as well. The energy consumption is also increased. Trunks also introduces the idea of losing the pupils during the transformation, which would surface once again with Broli in DBZ movie eight with the "Legendary" stage (see below). Trunks' raw power is actually greater than Vegeta's, in this form. Trunks holds off showcasing his new power until Vegeta is knocked unconscious, fearful of not only surpassing his father, but seeing the reaction from his father. Due to his lack of speed, while Trunks may have had the power to do battle with Perfect Cell, he simply was not able to keep up, and thus conceded.

GOKU

One would assume that if both Vegeta and Trunks could achieve this stage simply by training in the Room of Spirit and Time, Goku would be able to, as well... and he did. Goku is apparently able to reach both USSJ1 and USSJ2. However, Goku very quickly realizes the limitations of the stage (most notably the drop in speed and increased energy consumption). Other than simply showing it off to Gohan while training, Goku never actually uses this stage in fighting. Rather, he and Gohan develop the unique idea to realize Super Saiyan as their "natural" form, going about their daily activities (even sleeping!) as Super Saiyans. This was all in an attempt to become as comfortable with the form as possible, which would (in turn) allow them to conserve their energy while fighting, rather than having to worry about which stage they are in. See "Full Power Super Saiyan," below.

CHARACTER	NOTES
Vegeta	USSJ1 only DBZ Episode 155; Manga Chapter 377 In an incredible desire to surpass not only Goku, but the limitations of Super Saiyan, Vegeta's own training led him to surpass Super Saiyan while training with Trunks in the Room of Spirit and Time. Trunks hints that Vegeta may have been able to reach USSJ2, though we are never shown.
Trunks (Future)	USSJ1 and USSJ2 DBZ Episode 162; Manga Chapter 386 Training with his father in the Room of Spirit and Time, Trunks is also able to surpass Super Saiyan at an even stronger level than his father. Rather than embarrass his father, though, Trunks holds his "hidden powers" a secret until absolutely necessary; he holds onto USSJ until Vegeta passes out, and finally goes through the full "snap" into USSJ2.
Goku	USSJ1 and USSJ2 DBZ Episode 165, Manga Chapter 387 Training with Gohan in the Room of Spirit and Time after Vegeta and Trunks emerge, Goku comes across the stage, but quickly realizes that its disadvantages far outweigh the advantages, and instead turns his efforts towards training his son to reach a stage quite possibly even stronger than this...
THEORIES — CELL's CELLS
Cell	The Evidence... Cell twice showcases a form very similar to this. Very shortly after Trunks transforms into USSJ2 after Vegeta is defeated, Cell mocks him and his reliance on "brute force," and bulks up, himself. Later on, after SSJ2 Gohan pushes back Cell's giant Kamehameha with ease, Cell makes the exact same mistake that Vegeta and Trunks earlier made; he gets incredibly bulky in muscle size, which increases his strength... but drastically reduces his speed. Does Cell actually go USSJ? It makes sense, but ultimately, it's left up to the reader/viewer to decide...! For more information, check out Cell's own transformations page.

While training with Gohan in the Room of Spirit and Time, Goku becomes almost obsessed with having his son take over the reins as Earth's protector. Realizing the incredible, but dormant, power lying within his son, Goku pushes Gohan to his absolute limits (and in the anime even sees a quick glimpse of this power, which quickly disappears just as fast as it came).

Ultimately, the destruction wrought by Cell leads to Gohan's actual transformation into Super Saiyan 2. After destroying Jinzôningen #16, Cell unleashes seven "Cell Jrs." on the fighters. As Gohan watches in horror, too weak to do anything, as his friends are attacked, Mr. Satan tosses #16's decapitated head over to Gohan. #16 tells Gohan that he understands how he is feeling, but he needs to let it all out. It is time to protect the nature that he loved so much, and to protect his family and friends that he loved even more. When Cell crushes #16's head, Gohan's vision becomes completely clear. Belting out a scream from the depths of Hell, Gohan literally explodes into Super Saiyan 2 with tears in his eyes, determined to kill Cell.

Super Saiyan 2's most defining characteristic is the lightning that constantly surrounds and crackles around the character. The hair also stands much more on end (growing a little bit, as well). For Gohan and Goku, a single strand of hair falls over the eyes (since Vegeta's hair all stands up straight, anyway, this doesn't happen).

CHARACTER	NOTES
Gohan	DBZ Episode 184; Manga Chapter 409 Helpless to protect his friends, Gohan listens to #16 tell him to unleash that hidden power and protect the nature and friends that he loves so much. When Cell crushes #16's head, that's it... Gohan's ready.
(Majin) Vegeta	DBZ Episode 229; Manga Chapter 456 Vegeta allows Babidi to halfway take over his mind. Normally, Babidi would completely control the character; however, Vegeta retains control over his free will, yet also obtains the massive "power-up" from the "Majin" form. Vegeta's excuse is that he wants to return to his past, pure evil ways... in order to defeat "Kakarrot" once and for all. There are hints that Vegeta may have been able to transform into SSJ2 before the "Majin" charm, but there is absolutely nothing explicity said in either the anime or the manga.
Goku	DBZ Episode 229, Manga Chapter 458 Apparently having reached the stage while training in the afterlife, Goku is forced to also transform into Super Saiyan 2 when Majin Vegeta reaches the stage (without any hassle) during their climactic fight during the Buu arc.
THEORIES — FUSED CHARACTERS
Gotenks	The Evidence... We see Gotenks reach both SSJ1 and SSJ3; we have to assume that if he's able to reach SSJ3, there was an SSJ2 in there, somewhere! Daizenshuu # 7 states that Gotenks is indeed able to go SSJ2. So, while we never actually see Gotenks in SSJ2, it's safe to assume he can reach it.
Vegetto	The Evidence... By this point in the series, both Goku and Vegeta were able to reach SSJ2 (although, previously, Vegeta only went SSJ2 while under the "Majin" power-up). After Vegetto goes SSJ, he tends to have electricity surrounding him, a tip-off to SSJ2. Unfortunately, Vegetto never actually notes which stage he is in (beyond referring to himself as "Super Vegetto"); having two different stages of golden hair would help, but we just can't be sure. The second daizenshuu confirms that Vegetto is only in SSJ1, though he has a power greater than that of an SSJ3. Perhaps due to the magic of the fusion, his SSJ1 stage and its raw power takes on extra (later-stage) characteristics? It's quite possible he would be able to go SSJ2, though.
Gogeta	The Evidence... By this point in the series (when the movie would take place), both Goku and Vegeta were able to reach SSJ2 (although, previously, Vegeta only went SSJ2 while under the "Majin" power-up). Gogeta appears immediately in Super Saiyan, with no extra electricity surrounding him. It's quite possible he would be able to go SSJ2, though.

Super Saiyan 3 is, by far, the strangest transformation of the canon Toriyama storyline. Original concept designs show SSJ3 as having a tail, but the final design came to be as seen on the left.

Yet another stage that Goku apparently reaches in the afterlife while training, SSJ3 is an incredible strain on the dead and living body, alike (which is why when Goku uses the form, it reduces the 24-hour period he would normally be allowed to spend on Earth). Realizing the incredible power of the resurrected Majin Buu, and needing to stall for time, Goku shows Majin Buu SSJ1 and SSJ2... but notes there's more to show. Concentrating all of his energy, Goku lets loose a great scream. His hair begins to grown down his back and his eyebrows disappear. Lightning, similar to SSJ2, begins to surround his body. Just as SSJ1 and SSJ2, SSJ3 increases the raw power and speed of the character in exponential numbers. As noted, though, it is an incredible strain on the user (reducing Goku's time on Earth and reducing the fusion length of Gotenks).

Interestingly, Goku has black pupils with blue-green irises, while Gotenks only has the standard blue-green pupils; in fact, SSJ3 Goku is the only SSJ form (non-GT, fused or not) that has irises and pupils! In the manga, Toriyama makes heavy use of light screentone in areas that would otherwise be completely dark or shadowed; it's almost as if Goku is glowing all over!

The reasons for achieving SSJ3 are not actually noted, but seem to be attained by either incredible training for extended periods of time (Goku), or a combination of training and natural "magical" strength (Gotenks).

CHARACTER	NOTES
Goku	DB Episode 245; Manga Chapter 474 Apparently Goku's training in the afterlife for seven years brought him past SSJ1 & SSJ2 to a strange new level... SSJ3!
Gotenks	DBZ Episode 260; Manga Chapter 493 After sensing the incredible power of Goku while fighting as SSJ3, Goten and Trunks vow to reach that same level of awesome power. While training in the Room of Spirit and Time waiting for Majin Buu, the two achieve the level... but want to show it off at the last second for a grand finale!