Leonardo

Origin
See Origin.

1987 series
In the 1987 TV series' theme song lyrics, Leonardo is said outright to be the leader of the TMNT, and there is little disputing this; as such, his orders are usually followed, and he is a very serious do-gooder who hardly ever makes wise cracks, unlike his brothers (in one episode, his brothers actually hypnotized him to make him lighten up, only to find that he was too hyper and too much of a practical joker in his "relaxed" state and returned him to normal). In one episode, he suffered a crisis of confidence and left the group to do some soul searching; his brothers all tried their hands at being the leader in his stead, only to find that none of them could match his leadership skills, and he came back to them. He is often shown as the primary driver of the Turtles' van. He was attracted to a mercenary young woman named Lotus, a swordswoman prodigy from Japan who was hired by Krang to replace Shredder, whom she easily defeated (along with Rocksteady and Bebop). She and Leonardo dueled to a standstill before she resorted to a trick sword to knock him out. When they met the second time, she tried to convince him to join her as "ninjas for hire", but he refused. She turned on Krang and escaped to continue her mercenary lifestyle, telling Leonardo that there was little gold in goodness, though she hoped that they would one day be on the same side.

Leonardo also seems to enjoy reading. For example, many times when the Turtles are at home, Leo is reading a book. In the episode "Four Musketurtles", he is the only Turtle that read The Three Musketeers. Another good example is in "Leonardo is Missing"; while the other Turtles go to an arcade, Leonardo stays at the lair and reads a book.

In the original North American version of the 1987 cartoon show, Leonardo's voice actor is Cam Clarke (who also voiced Rocksteady).

Movies
In the first three TMNT movies, Leonardo was fairly modest and sensitive, rarely issuing direct commands; he also joked around with his brothers much more than in other versions of the TMNT. It was he who first communicated telepathically with a kidnapped Splinter in the first movie, but he was not ambushed by the Foot Clan (Raphael was), nor did he kill the Shredder. However, he is the only one of the four turtles to successfully injure Shredder during their climactic battle. He was acted by David Forman and voiced by Brian Tochi.

In both Teenage Mutant Ninja Turtles II: The Secret of the Ooze and Teenage Mutant Ninja Turtles III, his actor was Mark Caso and he was voiced again by Brian Tochi.

In the Fourth TMNT film, Leo was sent away by Master Splinter to hone his skills in becoming a more efficient leader after Shredder's defeat. April finds him in Central America, and while he was hesitant to return to New York City, he does at the right time to take on the dangerous new force of evil. His relationship with Raphael is strained due to Raphael feeling abandoned by Leo as well as feeling less loved by Splinter. Leonardo's vision of the world is perhaps also wider than Raphael's; in the first movie prequel comic, Leo becomes angry with Raphael for trying to leave them in order to save a man from being mugged, because there are four heavily armed Triceratons in the sewers who could cause devastation to the city. He becomes further angered when Raphael deserts them mid-battle to help the old man get home safely. This conflict suggests that the two brothers operate on different levels of morality, though neither is necessarily wrong. Raphael states in the comic that he was tired of waiting for disaster to fall on his family, and tired of fighting aliens while people in their own neighborhood are being mugged and murdered. Leonardo, on the other hand, believes that the world of men is the responsibility of the police, while Utroms and Triceratons are their domain, and that they should fight only when there is no one else who could solve the problem. This also engages Leo in a contradiction when he stays in Central America, using violence to fight local lawlessness and effectively deserting his brothers because he believes, as Raphael believes, that others need him more. Such parallels suggest that the two brothers are experiencing the same dedication to justice but in different mentality, albeit in very different locales and using different tactics. In the TMNT CGI movie, Raphael challenges Leonardo after arguing of their own individual sense of justice and the reasons for their actions, Leo also discovers that Raphael is the Nightwatcher, and they engage in a fight. Distracted when Raphael breaks his swords he is pinned to the floor. Raphael almost kills Leo, then retreats due to his bothers deep and confused stare. Leonardo is captured by the War Generals and Foot Clan but is rescued by his family later before the final battle where Leonardo and Raphael finally resolve their differences, Raphael accepting Leo as their leader while Leonardo confesses to needing Raphael. Leonardo is voiced by James Arnold Taylor in this film.

The Next Mutation
In 1997-1998, Leonardo along with the other Ninja Turtles were featured in a short-lived live-action series. He also carried one double bladed ninjaken instead of two. His sibling rivalry with Raphael drove many episodes. In one episode where they were sparring, Raphael took advantage of Leo's apparent physical weakening, insulting, mocking and taunting his brother to make him more reckless, until finally Leo lost his temper and angrily kicked Raph so hard that he sent Raph flying across the sewer den; they spent the rest of the episode arguing and challening each other to tests of skill (some of them quite absurd) until finally using arm wrestling to decide who would live in the sewer and who would leave. Although Leo won, it was decided that Raph should stay.

2003 series
In the new Mirage Studios and 4Kids Entertainment 2003 animated TV series, Leonardo is voiced by Michael Sinterniklaas. He is the de facto leader of the group and the most "spiritual" of the four TMNT. He has a very close bond with Splinter, and has a strong sense of honor, ethics, and Bushido; episodes that deal with The Shredder and honor usually also focus on Leonardo, and he is often the Turtle who "saves the day." Leonardo is a more sensitive, self-doubting character than in previous incarnations. Raphael often quarrels with him and resents his leadership, sarcastically calling Leonardo "Fearless Leader," although the two are shown to be very close at times. Though Leonardo's relationships with his other brothers Michelangelo and Donatello are not as volatile, both have made comments alluding to the high standards the former has set, and his tendency to make them look bad. Despite this, his brothers view him as a pillar of strength, and are at a loss when he is injured or absent. One of Leonardo's most prominent qualities is his determination to believe the best in people, even potential enemies (i.e., Karai, Traximus, Quarry).

At times, Leonardo is shown to be very hard on himself, as he feels that a lot is expected of him. As in the comics, Leonardo is ambushed and seriously injured by the Foot Clan, and he feels he let his family and himself down. He has the same feelings after the final battle with the Shredder - his anger and self-doubt was caused by Karai, whom he believed was an honorable ally, but she was unable to go against her master's evil orders, eventually causing her to stab Leonardo (albeit unintentionally). Leonardo also feels extremely inadequate, as he believes that again, he let himself and his family down, this time by finding no other way to destroy the Shredder than to blow up the spaceship that both the Shredder and the Turtles were on; the Turtles and Splinter would have perished if they had not been rescued by Utroms. Eventually, Leonardo finds inner peace under the guidance of the Ancient One, who trained Splinter's sensei, Hamato Yoshi. From their final battle with the Shredder, Leonardo was the only turtle to sustain truly lasting damage; part of his shell on his upper left shoulder had its edge shorn off. Nevertheless, he is arguably the most skilled of the Turtles, being the only one trained by two senseis, and is capable of facing and defeating Karai, the new Shredder, in a one-on-one fight.

Lost Season
In the fifth season, of the eight acolytes under the Ninja Tribunal's training, Leonardo is the only one who isn't given one of the Fangs of the Dragon, which are upgraded versions of each acolyte's weapon. This may be due to the fact that his otherworldly form is that of a dragon, a rare form, unheard of in someone his age. It is shown destroying all the evil guarding the second artifact. This avatar is first shown in "More Worlds Than One". In the fifth episode "Beginning of the End," he is given Feragi's sword as the warrior dies. But when it is revealed the four acolytes survived the mystical ninja attacks Leo returns the sword and goes back to using his ninja swords.

Fast Forward
In Fast Forward, the damage that occurred to Leonardo's shell as stated above has disappeared.