Exiled to a toxic waste dump world reserved for Dimension X's most dangerous criminals, Slash, an eco-terrorist from the planet Palmadise who met and befriended Krang and Bellybomb. They escaped the waste ship and headed for Earth where they fought, and were defeated by the Teenage Mutant Ninja Turtles.
Slash later resurfaced in a state of berserker rage in South America and took a bomb being dropped on him just to render him unconscious. The Mutanimals finds a newspaper about the event and believing Slash to be one of the Ninja Turtles, break him out of his cage. When Slash regained consciousness he attacks the Mutanimals, but is subdued by Leatherhead. The Mutanimals discover that Slash's world was strip-mined and that all he really wanted was to live in a place that reminded him of home where he could live in peace. The Mutanimals bring him to an environmentally protected island, and Slash was finally at peace. That was until the Mutanimals were killed in cold blood by Mr. Null's Gang of Four. Slash, the Ninja Turtles, Ninjara, Future Raph, Future Don, and Master Splinter joined forces to avenge the Mutanimals and stop Null, Maligna, and their henchmen from destroying Earth.
In the end, Slash died when he refused to leave Maligna's hive which was crashing into the sun in order to make sure Maligna and Null didn't escape. The Teenage Mutant Ninja Turtles, Kid Terra, April O'Neil, Oyuki, the future TMNT, Ninjara, Splinter and a couple others held a funeral for him and honored Slash as the fifth Ninja Turtle in a sunset memorial ceremony. It is unclear at this point if Slash will surface in new TMNT comics.
Slash has demonstrated super-strength, invulnerability, and expertise skills with a katana, bo, sai, and nunchaku. He is adept with every weapon that the TMNT wields, as well as Pantera claws similar to those used by Shredder. Slash is short tempered and has been known to fall into berserker rage, he seems to grow only stronger while in this state and has been depicted of fighting off all four Ninja Turtles.
Teenage Mutant Ninja Turtles (1987 Animated TV Series)
Slash appears in the original Teenage Mutant Ninja Turtles animated series as Bebop and Rocksteady's creation to complete tasks Shredder assigns them that they don't want to do. He is considered to a very strong mutant turtle who is obsessed with trees like in other versions. Bebop and Rocksteady, who exposed Slash to mutagen, one day aggravated him to the point he went berserk, stealing some of Shredder's weaponry and fled to Earth where he played has an enemy of the Ninja Turtles.
Teenage Mutant Ninja Turtles (2014 Animated TV Series)
Slash appears first as Spike, the turtle pet of Raphael. In the episode "Slash and Destroy" Spike mutated into Slash. he later became an ally to the TMNT.
Slash appears as a boss in both the NES game Teenage Mutant Ninja Turtles III: The Manhattan Project and in the Super Nintendo version of Teenage Mutant Ninja Turtles IV: Turtles in Time at the end of the prehistoric level, which he is considered one of the games most difficult bosses as he blocks most of the player's attacks.
Compared to other TMNT characters, Slash has had relatively few collectibles released based on him over the years, to date he only has a single action figure by Playmates Toys, a Dress-Up Kit which included a Black Bandana with a turtle "nose" sewn on, a pair of plastic claws, and black "foot clan" knee pads and elbow pads, and a glow in the "pre-mutated" turtle that was included with cans of purple matagen goo.