Donatello

Donatello is a mutant turtle and one of the main characters of the series. The color of his mask is purple and his weapon of choice is a bo staff. He is voiced by Rob Paulsen, who is known for the voice of Raphael in the 1987 series.

Physical appearance
Donnie (or Don) is a slender turtle with a purple mask and belts. His skin is a lighter green, and he has a gap between his teeth.

Personality
Donnie was the brains of the team. He knows a lot about science and can even make his own inventions (like the T-Phone, Metalhead, etc.). He also has a crush on April. Like all of the turtles, he enjoys pizza.

Early life
Like the rest of the turtles, Donnie was adopted by Splinter when he was a normal turtle. They were then drenched by mutagen from some Kraang disguised as people. They moved to the sewers and they were trained as ninjas. Splinter then named all of his sons after the Great Renaissance artists.

April
April is Donnie's big crush. He has fallen in love with her. He attempts to protect her from danger, and sometimes wants to hang out with her. He also wants to make himself look cool around her.

In The Mutation Situation, she got upset and angry at the Turtles for mutating her father (by accident), which broke Donnie's heart. Later on in Target: April O'Neil, she apologized to the Turtles after they saved her from Karai. She thanked Donnie for always being there, even when she didn't wanted to. She gives Don a hug, and then she kisses him, much to his joy.

Casey
Donnie is not always happy with Casey around. He became jealous when April was spending more time with Casey. He always has an arguement with him whenever something goes wrong between them and April.

He also feels bad for Casey whenever he is lost (such as being abducted by a giant rat and swallowed by a Kraathatrogon), and it makes April sad. Donnie and Casey rarely get a long, but they're still trying to be friends.

Leatherhead
Donnie is mostly feared with Leatherhead around because of the running gag that involves Leatherhead grabbing Donnie's face and shaking him like a rag doll whenever he gets angry around the Turtles. Leatherhead feels regretful of what he did.

Metalhead
Donnie loved his new invention, and felt very proud. He can also upgrade his robot and program him. He also had Metalhead program himself. He is also quite upset for the way Leo don't trust him, and thinking he's dangerous. However, at the end of Metalhead Rewired, the brave robot sacrificed himself to save them and the mutants from the Kraang, much to Donnie's sadness, and Leo took back of what he said. But don't worry. Don might make a new Metalhead in the future.

Kirby
He is sometimes seen around with Kirby, while talking about April. Like Donnie, Kirby seems to know a lot about science. When he got mutated, Donnie scolded Mikey for trying to give Mr. O'Neil a monster name. The mutation of Kirby caused April to temporarily break the Turtles' friendship. Donnie even saved Kirby from the Kraang. He even created a retro-mutagen that will allow Kirby to transform back to human.

Timothy
He was quite annoyed of Timothy's clumsiness and wanting to mutate himself to be like the Turtles. Obviously, Donnie and the Turtles were surprised that he worked with the Foot. Upon his mutation, he and the Turtles tried to calm him down to bring him back memories. Even though he foolishly mutated himself, Donnie promised that he will turn him back. When Timothy grew arms and legs inside his container after drinking some ooze, Donnie thought he was trying to get April back, but only to reveal that Timothy only wanted to make April his friend, not the Turtles'. Even when Timothy was froze by an unstable type of mutagen, Donnie felt depressed, but he still promises to find a cure.

Trivia

 * Donnie knows almost everything about science. He even has a lab of his own.
 * He was named after Donatello di Niccolò di Betto.
 * Donnie's worst fear is April rejecting him.