They were originally human, part of a street gang in New York City that was employed by Shredder. Rocksteady was originally a short and stocky blond Caucasian man (who sported army camouflage pants that would be replaced with simple beige cargo pants later while also occasionally sporting a strong Army helmet on his head in his mutated form). Bebop was a taller African American man with a purple mohawk. With the other members of their gang, they were sent out to stop a Channel 6 reporter named April O'Neil from doing a report about crime in the city. April ran down into the sewers while being chased by the street gang and met the Teenage Mutant Ninja Turtles, who then defeated the gang in a fight.
After this humiliating setback, The Shredder developed a plan to defeat the Turtles by mutating members of the street gang, so that they would have abilities parallel to the Turtles'. Bebop and Rocksteady both volunteered to undergo the procedure (though neither was particularly aware of what it would entail) with the promise that it would allow them to exact revenge on the Turtles. Bebop was mutated into a human warthog, and Rocksteady into a rhinoceros. However, though the transformation did make them larger and stronger, they remained incompetent simpletons and were completely inept at stopping the Turtles or carrying out Shredder's plans. For example, in "Enter the Shredder" they charged at the Turtles, who jumped, and crashed they into each other. Donatello commented that their mutations didn't "up their IQ's any." For most of the series they were employed for the Foot Clan's purposes however, the Turtles certainly consider them to be formidable (despite their stupidity) in combat due to their great strength and endurance, and as such, often use their intelligence to outwit them rather than fighting them in a straightforward manner. In one episode of the series, Bebop was shown to have kept a pet turtle, which got mutated into the evil turtle Slash.
Bebop and Rocksteady's last appearance is in the season 8 finale Turtle Trek. In that episode, the Turtles destroy the Technodrome's engines, trapping it and its inhabitants in Dimension X for good. Bebop and Rocksteady are never seen again after that episode, but Krang and Shredder return during the 10th and last season. Bebop and Rocksteady are presumed to still be somewhere in Dimension X.
They made a reappearance in the made-for-TV movie Turtles Forever. Their incompetence is still shown, although it ended up saving the 2003 Shredder when Rocksteady accidentally tripped over and unplugged a laser that was about to destroy him, although Bebop ended up obliterating the 2003 Shredder anyway when he re-plugged the same laser device all the while thinking he would be pleased that they "fixed" his machine.
In the 2012 Nickelodeon series, Bebop and Rocksteady were introduced as master thief, Anton Zeck, and Russian arms dealer, Ivan Steranko. Steranko first appeared in "Enemy of My Enemy" making a deal with the Shredder, until defeated by the weapon he was selling. He and Zeck both appeared in "The Legend of the Kuro Kabuto", in which Steranko hired Zeck to steal Shredder's helmet (the titular object). Zeck managed to break into Shredder's lair and steal the helmet, only to be accidentally run over by the TMNT and have the helmet stolen from him. He later chased after Leonardo, who gave him the helmet so that Rahzar, Fish-Face, Tiger Claw and StockmanFly would pursue him instead. Zeck was then saved by Steranko, only to discover that Leo had switched the helmet with a bag of dirty diapers at the last minute. Steranko and Zeck next appeared in "Serpent Hunt" as two of the few humans left in New York after the Kraang invasion. Starved and desperate, the two tried to escape New York by capturing Karai (who was mutated into a snake and was missing) and giving her to Shredder in-exchange for leaving the city. The duo eventually capture Karai and bring her to the docks to make the deal with Shredder, only to be interrupted by the turtles, resulting in them being captured by Shredder and his minions. Furious after they kidnapped Karai and learning Steranko was behind the theft of his helmet, Shredder and his minions threw the duo into a vat of Stockman's specially prepared mutagen and mutated them into a warthog and a rhino. In the next episode "The Pig and the Rhino", which takes place directly after the last one, Steranko and Zeck are furious after their mutation and try to attack Shredder, only to be easily defeated. After being forced to work for Shredder, Zeck and Steranko are sent to recapture Karai and bring her to him, only to neglect this duty to seek vengeance on the turtles for ruining their deal at the docks. They soon systematically defeat Donatello, April, Raphael and Casey Jones, kidnap them and steal their T-phones in order to locate the remaining two. After tracking Michelangelo and Leonardo to Coney Island, the duo try to lure them out by threatening their friends, only for Leonardo to free them while being distracted by Mikey's attempts to give the mutant names, eventually seeing an advertisement for a Bebop and Rocksteady concert, and giving them those names. Realizing that they've been tricked, Bebop and Rocksteady try to use the turtle's retro-mutagen to cure themselves, only to be defeated by the turtles, April, Casey, and Snake-Karai. After that, the two encounter Karai again and capture her, completing their mission. In the "Noxious Avenger", Bebop and Rocksteady battle the turtles on a rooftop and accidentally drop a canister of mutagen on local sewer worker, Garson Grunge, mutating him in to Muck-Man. Fed up with being bossed around by Shredder and his henchmen, the duo manipulate Garson int thinking the turtles mutated him and use him to carry out their own nefarious deeds, until the truth is revealed and they are defeated. In "Attack of the Mega Shredder", after Leo and Mikey are captured by the Foot Clan, Bebop and Rocksteady watch them while Shredder and his minions are preparing to "double-mutate" them, only to be tricked into throwing the three Shredder mutants into the vat planning to combine them with the turtles to create a giant super mutant, but instead create the titular Mega Shredder. In "Annihilation Earth Part 2" Bebop captures April when her and Splinter try to infiltrate Shredder's lair and convince him to help them fight off the Triceraton Empire and joins him and his other minions when they decide to team up. Bebop and Rocksteady are both killed, along with everyone except the turtles, April and Casey, when Shredder literally back stabs everyone by killing Splinter and preventing him from stopping the Black Hole Generator, however, they are saved when the six survivors and the alien cyborg, the Fugitoid, time travel and prevent Shredder from killing Splinter and the Black Hole Generator from going off. In "City at War" they are seen guarding the now sick and dying Shredder at the end of the episode. In the next episode, "Broken Foot", they accompany Tiger Claw and help him protect the Alumon Chemicals factory and the Foot-Bot assembly factory from Karai, Shinigami, Leonardo and the other turtles.
Bebop and Rocksteady will make their debut in a live-action TMNT film in Out of the Shadows.
In the trailer, they arrive where the Ninja Turtles are. Leonardo, Raphael and Donatello are all scared stiff by their appearance, while Michelangelo compliments Bebop for bringing back the mo-hawk. Bebop gets annoyed that they're not being taken seriously, and they charge at the turtles with Bebop tackling Leonardo and Rocksteady tackling Raphael to the ground. The two will be equipped with their own motorcycles and Rocksteady is seen chasing Casey Jones in a parking garage on foot while hurling away the cars he barges into to catch Casey. Rocksteady also commandeered a tank and attacks the Turtles using it in a river.
- Bebop and Rocksteady were originally supposed to appear in Secret of the Ooze, however, due to copyright problems, they were replaced by the two new mutants, Tokka and Rahzar.
- In the 2003 series, while on the Turtle's earth, the Usagi Yojimbo character/anthropomorphic rhino, Gen, dressed up like Rocksteady.
- In the SNES version of Turtles in Time, Bebop and Rocksteady appear on the Pirate stage instead of Tokka and Rahzar, who previously appeared in the SNES only Technodrome stage. For some reason, Bebop and Rocksteady were never in the original arcade game.
- Bebop and Rocksteady were hinted at and referenced before hand in the 2012 series, most notably when Baxter Stockman said he wanted to create mutant pigs and rhinos, which he actually got to do.
- In the 2012 series, Bebop and Rocksteady, along with Mondo Gecko, appeared in the new intro for season 3, several episodes before their first appearance.
- In "The Noxious Avenger", Bebop says the line "I'm outie 5000." This is supposedly a reference/shout out to YouTuber Andre "Black Nerd", who is a huge fan of the Ninja Turtles and frequently reviews episodes of the show, including this one, where he stated that someone who worked on the show said that he might like a certain phrase said in the episode.