Leonardo

Physical appearance: Leonardo is presented to be a vibrant lime green skinned terrapin mutant/yokai who possesses the features of a Red-Eared Slider, he is the second tallest of his team. (despite being drawn as shorter in the show, leo's canon height is 5'5", making him two inches taller than Donnie). He, much like his brothers, sports an altered human-like physique consisting of sculpted, medium-sized figure. Having three fingers on each hand, and two toes on each foot. His slider features consist of light yellow stripe-like markings running down his thighs and arms, sporting two on the sides of his shoulder blades, whilst the other two reside on the sides of his upper thighs. He follows with two red crescent-shaped markings imprinted just on the outer edges of his eyes, having a Goldenrod yellow plastron, as well as a dullish blue grey carapace that has a somewhat darker outer trim around the edges. Plastered on the back is a three-numbered steel blue pattern that resembles closely to the curly bracket symbol: {}, His eyes are onyx and often rather slanted.

Leo wears a Dodger Blue mask that has back-length bandana tails reaching behind his back, his forearms donning dark teal fingerless gloves which have a matching dodger blue trim outlined on both sides. The socks on his legs having a matching scheme, reaching just below his knee. The sock lacks coverage on his ankle and toe as well, finishing his attire with a matching blue belt that has two holsters on the back and side, a strap perched on the left of his shoulder. Finally, the turtle emblem is located partially on the right of his plastron.

When his Hamato Ninpō is unlocked and since the film, his fingerless gloves, knee-high socks, and belt with the strap are black, and one pouch remains on the back.

Personality: Leo is prone to make jokes and sarcastic remarks, often during inappropriate times, which can sometimes leave his brothers annoyed and frustrated towards him. Leo has a tough time taking things seriously, especially during the times he puts his full faith on himself rather than his team.

Leo has confidence that usually turns into arrogance and his brothers are often annoyed by his lack of humility, making him difficult to play games with such as in "Lair Games".

Leo is at times rational and skeptical, denying the existence of things like ghosts and wanting to search for a logical answer as opposed to accrediting it to unexplainable phenomena. Despite this, he is delighted by magic and mystic powers as seen in “Hypno! Part Deux”. He also seems to be the least naïve out of the Mad Dogs as his brothers trust Big Mama almost instantly, though Leo has his doubts about her intentions. However, Leo's tendency to be easily impressed and incessant need for attention can hamper his caution.

Leo is very strategic with his plans and formulating ideas, noticing when Raph's leadership fails, he comes from the background to show everyone how its really done. While Leo has merit, his utilization of his skills often needs to be spurred by a dire situation or a lack of options as opposed to Leo trying his best when he can. When he does decide to be serious and sensible, as in the events of "Origami Tsunami", he uses his charisma and relaxed, flexible nature to sway his brothers into listening to him.

Leo is irresponsible and known to be generally unreliable among his family due to how flippant he can be even in grave situations and finds it very difficult to take responsibility for his actions while also being boastful about his positive or impressive actions. Although he has been shown to try to reconcile his mistakes and be sympathetic towards others’ plights such as in “Bullhop” by inviting Bullhop to live with his family and trying to gather the Mad Dogs' continued support for him despite their own reservations for accidentally causing his mutation.

Leo demonstrates forte in analytical thinking as shown in “Many Unhappy Returns”, able to plan several steps ahead of Big Mama, but he can be so determined to successfully execute his plans while also having glory that he uses his allies instead of working with them and is comfortable misleading his allies and opponents alike to his achieve goals such as in “Air Turtle”.

Upon Rise of the Teenage Mutant Ninja Turtles: The Movie, Leo's character flaws are put to the test where his overall immaturity and self-doubt had allowed the Foot Clan to steal the Mystic Key and unleashed the Krang. This lead him to be berated by Raph for his misunderstood ego, and his student-from-the-future, Casey Jones for failing to be the responsible master he always looked up to. Leo finally accepts his own faults with humility when he confronts a zombified-Raph and acknowledges the true meaning of teamwork, responsibility of a leader, and family.

It's also revealed in Rise of the Teenage Mutant Ninja Turtles: The Movie that this arrogant personality may be a façade to hide Leo's deeper insecurities. This was lightly foreshadowed before in episodes like Portal Jacked!, where he states that he is nothing without his brothers, Minotaur Maze, where he calls himself useless, and when he asks Splinter why no one seems to trust him in Many Unhappy Returns. He has also stated in Mystic Mayhem that his unnecessary jokes and teases are a coping mechanism, and a way to hide any sign of fear from himself in situations. This shows that Leo tries hard to maintain a 'chilled and arrogant' persona, rather than showing any fear.

By the end of the film, Leo had completely changed & redeemed himself. While still keeping his lightning witted sense of humor, He matured into a responsible, noble and selfless leader and a better brother.