Splinter was the pet rat of Hamato Yoshi in Japan who learned the teachings of his owner from his cage. When Hamato Yoshi was killed by Oroku Saki, Splinter escaped his cage and clawed at the murderer's face, causing an enraged Saki to slice his right ear off.
After his master's death, Splinter found himself in the sewers of New York City of New York City where he found four baby turtles. One morning Splinter awoke to find the turtles playing in a glowing green "goo" spilling out of a broken canister. The five were quickly affected by this substance, growing in size and intelligence. Once they had fully mutated, Splinter taught his Turtle sons the the ways of honor and the path of the ninja.
Teenage Mutant Ninja Turtles
After his sons returned from their first battle, Splinter expressed concern that they had been seen, and reminded them of the way of the ninja. However, he was exasperated by Michelangelo interrupting his speech to order pizza, and then eschewing meditation to dance. Later that night, he waited for Raphael to return their home, speaking to his son about the difficulties of facing his anger.
When Raphael brought an unconscious April O'Neil back to the lair, Splinter cared for her until she woke, and attempted to reassure her when she panicked. He told her the story of how they were mutated and introduced the Turtles to her by name.
However, while the Turtles took April back to her apartment, the Foot Clan invaded the lair and kidnapped Splinter, taking him back to the warehouse where they were headquartered. He was left chained to a wall, starved and weakened, for several days. During this time, he made the acquaintance of a young Foot Clan member named Danny Pennington, and convinced him to leave the clan. He also revealed to the boy another part of his history, namely the murder of his master by the Shredder.
During the Turtles' exile to the countryside, Leonardo psychically connected to Splinter while meditating. The Turtles all managed to connect with their beloved master as well, allowing Splinter to reassure them and tell them of his love for them.
Upon learning of the Turtles' return to New York, the Shredder ordered Splinter to be killed. Before Tatsu could do so, Splinter was freed by Danny and Casey Jones, and managed to convince the Shredder's young followers that he was only using them. He then made his way to the place where the Shredder was battling all four of the Turtles, and revealed that he was none other than the rat who had disfigured the man's face. Shredder is going to finish what he began with Splinter's ear by charging at Splinter with the yari to impale him. Splinter uses one of Michelangelo's nunchucks to wrap the yari and to send Shredder over the side of the roof. Shredder tried a final attempt to kill Splinter by trying to stab him with a tanto. But, Splinter sent him falling into a garbage truck.
With that, he was reunited with his sons, and watched as they celebrated their victory.
Teenage Mutant Ninja Turtles II: The Secret of the Ooze
Along with his sons, Splinter temporarily stayed with April O'Neil in her new apartment, though unlike them he attempted to be a good guest and minimize the impact on her life. He sternly reminded his sons that they were still ninja, and that the outside world would not understand or accept them.
After seeing April's coverage of the TGRI cleanup, he chose to finally reveal that the canister of mutagenic ooze came from that same company. When the Turtles were later about to be killed by the Shredder, Splinter intervened just long enough to free them, though he did not otherwise contribute to the battle.
Upon his sons successfully freeing Dr. Jordan Perry, Donatello became depressed over the revelation that the mutagen was simply a lab accident, and that there was evidently nothing more "special" about their origin as mutants. Splinter attempted to comfort his son by assuring him that his worth is not dependent on his origins. And told him that such a journey didn't always have such an easy answer and stated that a search would have to wait.
At the story's conclusion, Splinter confronts the Turtles with a front-page picture of them fighting at a nightclub, where hundreds of people saw them clearly.
Teenage Mutant Ninja Turtles III
In the 2007 CGI film he had once again reverted to his origins of the dignified master, and father with only a handful of humorous scenes in his role. Splinter sent Leonardo on a long journey to improve his skills. After his return, the Turtles brothers were back together, and he fought with them to defeat the Stone Generals. He was also more expectant of Leonardo to take up the task of bringing the Turtles back together.
- According to the T files on the 1990 movie DVD extras, Splinter's:
- Hobbies are reading and cooking.
- Favorite types of music are traditional Japanese music and Reggae.
- Favorite foods are fresh vegetables and cheese.
- Favorite book is "The Chrysanthemum and the Sword" by Ruth Benedict.
- Height is 5'2.
- Weight is 115 lbs.
- Eyes are brown.
- Is left-handed.
- Is partial to both purple and yellow as his favorite colors.