Splinter is the tritagonist of the original 1990 Teenage Mutant Ninja Turtles film, and a supporting character in the sequels.
He is both voiced and perfromed by Kevin Clash in the first two films, who also voiced and perfromed for Elmo from Seasume Street, James Murray in the third film and voiced by the late Mako Iwamatsu in the CGI fourth film, who also provided the voice for Iroh in the first two seasons of Avatar: The Last Airbender.
Teenage Mutant Ninja Turtles
15 years ago in Japan, a man named Hamato Yoshi was Japan's finest warrior. His pet rat who will be named Splinter mimics his every movement and takes it by heart. Yoshi's rivalry was a man named Oroku Saki whom he competed with especially for the love of a woman named Tang Shin, but Shin only loves Yoshi. Instead of fighting Saki in honor, he flees with Shin along with Splinter to New York City, but Saki followed as he killed Shin first and killed Yoshi right after he returned home who witness his beloved's murder, which causes Splinter's cage to be destroyed as Splinter jumps out and attack Saki by clawing into his face, but Saki threw Splinter to the ground and sliced Splinter's ear with his katana.
With Splinter all alone, he finds himself in a sewer searching for food until he noticed four baby turtles that were covered in ooze, so Splinter took them and raise them. The next morning the turtles had doubled in size as well as Splinter becoming more intelligent. As time goes by the turtles grew as they learn to stand in two feet and speak, with Splinter teaching them everything his master has taught them and gave them all names such as Leonardo, Michelangelo, Donatello, and Raphael.
After the Turtles mastered there first victory in battling a gang of street thugs without being seen, Splinter informed them that they must learn to work together as a whole because there will be a time where he will no longer be with them, but there teenage aspects had them decide to celebrate eating a pizza, while an angry Raphael decided to go to a movie to let off some steam after being frustated for losing one his sai during the fight.
After Raph return home from the movie, and a brief confrontation with Casey Jones, Splinter have a pep talk with about learning to control his anger.
The next day, after Raphael saved reporter April O'Neil from a mysterious group of ninjas called the Foot, he takes her back to there layer, where Splinter had the Turtles wake her up with water.
She was frighten at first, but Splinter tells her about how they came to be. While April decided to invite the Turtles to her home, Splinter was abducted by the Foot, and taken to there hideout on the eastside of town, where delinquent children and teenagers hangout while being train to become a member of the Foot under the leadership of the Shredder, who is secretly Oroku Saki. Splinter was being chained to a fence while the Shredder demand his fellow Foot to hunt down the Turtles and punishing them for there interferance.
After their first failed attempt in defeating the Turtles, an angry Shredder demanded Splinter of their Turtles fighting abilities, but he refused to answer.
Splinter then meets with one of the delinquent children name Danny Pennington who is the son of April's boss Charles. When Splinter asked the whereabouts of his parents, Danny claims that his father couldn't care less, but Splinter implys that he doubts because deep down all fathers care for their sons.
After Leonardo gets a reading to know that Splinter his alive through meditating, he gathers the others Turtles in a campfire where they meditate through the spiritual wisdom of Splinter through the fire who informs how proud he is of them for learning to work together as a family believing that they would no longer need him.
He meets up with Danny again tells him his backstory about incident that led to him losing his master Hamato Yoshi by the hands of Oroku Saki, and when Splinter tells him that he was wearing the symbol of the Saki on his bandana, he drops it and decided to leave the Foot until he was confronted by the Shredder who saw that he had a drawing of Leonardo in his pocket to realize that the Turtles has return and rallies to Foot to go after them with Shredder leading this time.
Meanwhile Danny and vigulante Casey Jones help Splinter escape by removing the chains, not before being confronted by Shredder's second in command Tatsu and the remaining deliquent children.
After a brief confrontation between Casey and Tatsu which ends with Casey using a golf club to knock Tatsu unconcious, Splinter informs the outcasts that Shredder has no care and affaction for them, and only used them for his personal agenda.
After Danny and Casey help Splinter on his feet, they return near the sewer, and witness the Turtles being outmatched by the Shredder, which forces Splinter to confront the Shredder and reveals that he knows he is Oroku Saki which gives Shredder PTSD flashback as he remove the faceplate which reveals the same scar Splinter gave that long ago, and states that he is going to finish what he began with Splinter's ear, as he charged his sharped bo staff at him, but with Splinter dodging it with one of Michaelangleos nunchucks.
As Splinter makes a speech about how Saki would die without honor, Shredder was about to use one of his trump cards to make the final blow, but Splinter grabbed on to it causing Saki to plummet down a trash compactor as Casey used it to crush him inside.
With the Turtles and Splinter reuniting, Splinter gives the Turtles the famous Cowabunga catch phase, and states that he had made a funny.
Teenage Mutant Ninja Turtles II: The Secret of the Ooze
With the defeat of the Shredder and few of the remaining still out searching for the Turtles, the Turtles and Splinter decided to stay at April's new apartment while still hoping to find a new place to live.
One morning when the Turtles were watching a report about T.G.R.I., Splinter revealed to them that it was the same company that transformed them into what they are, and must further seek out the information about there origin. After failed attempt, due to there confrontation with the Foot along with them abducting the head scientist: Professor Jordan Perry, the Turtles and Splinter realized that the can no longer stay at April's in fear for her safety, but got an unexpected visit from April's local pizza delivery boy Keno, where after getting over the shock of seeing them, he informed them about new recruits for the Foot, with him and Raphael convincing the others that if he joins, he can infiltrate there secrets, but Splinter refuse, which frustrates Raph as it force him to separate from the others. Splinter would later appear freeing his son from a net that the Shredder (who was revealed to be alive), use to drop them with a pack of Spikes. Splinter immediately leaves them to do their thing as they deal with the Foot and two new giant mutants from an alligator snapping turtle and a gray wolf name Tokka and Rahzar, which the Shredder had Professor Perry create against his will, in order to kill the Turtles.
After the Turtles saved the professor, and sends him to their new home down the sewers Perry informed them that the ooze was a mistake which upsets Donatello who thought there existence would've meant something more, but Splinter states that they shouldn't be define by their origin. After Perry develop an antidote to de-mutate Tokka and Rahzar to their original selves for the Turtles to go and confront them with, Splinter meditates with Keno, but due to Keno's lack of patience, he leaves to help the others.
Later when sat to watch the News, he is distraught when he learns that the Turtles revealed to themselves in public and punished them to do ten back flips, and tells them 'Go Ninja Go Ninja Go!', and laughed stating that he made another funny.
Teenage Mutant Ninja Turtles III
The Turtles (with the expectation of Raph) and Splinter were enjoying their new home in the sewers. When April stop by to give each of them gifts as she leaves to go on vacation, she gives Splinter an ancient Japanese scepter that glows which caused her to go back in time to Feudal Japan, as she was replace by a young Japanese samurai name Kenshin wearing her clothes, as April did his.
When the Turtles attempt to go back to save April, they were replace by four Honor Guards that Splinter and Casey had to watch over. After a moment with Kenshin who asked Splinter what is wrong, he tells them that he sense danger from the past. As the scepter glows realizing that it is time, Kenshin attempts to leave immediately, but Splinter informs not to leave without the Honor Guards (who were going around New York), as it would be too cowardly. The Honor Guards did rush there way back as they all grabbed hold, as do the Turtles and April, and they all switched back from their regular lives.
Michelangelo who almost didn't make it back, was shown to be upset that he had to leave mainly due to his romantic infatuation with Kenshin's girlfriend Mitsu, but Splinter cheered him by were a lampshade and doing Elvis Presley impressions.
Splinter also appears in the 2007 CGI movie, albeit scarcely. He sends Leonardo on a long journey to improve his skills. After the latter returns, Splinter fights the Stone Generals with the Turtles. He also expects more in Leonardo to unite his brothers.