Donatello has green skin and russet eyes. He wears brown straps across his waist and across his chest.
Donnie is extremely intelligent and technical, always working on a strategy whether building machines or battling villains; the complete opposite to the free-flowing Michelangelo. He talks a lot in order to describe or explain a situation or theory in full, even when in the face of danger. He is also more short-tempered, getting frustrated easily and shouting when angry, although Donatello is usually kind, caring, and compassionate. He is very protective and complimentary of April O'Neil whom he has a huge crush on. At times does not understand or has a hard time grasping the lectures of Master Splinter.
Hamato Yoshi bought the four young turtles at a pet shop. On his way out the shop, he caught sight of a Kraangdroid, and in the ensuing altercation, Yoshi and the turtles were infected by a canister of mutagen, mutating him into an anthropomorphic rat and the turtles, respectively. They made their home in the sewers underneath New York City, hiding from the public for the next several years
- Leonardo - Donnie's oldest brother. He and Leo rarely fight, unless absolutely necessary. They do tend to tease each other often, but never try to hurt each other physically. Although, there are points in the series where Leo tends to stress out Donnie while he fixes or opens bombs, locks, etc. Donnie, in return, questions Leo occasionally about his plans to see if they're accurate or safe. Leo feels like Donnie worries too much, and Donnie feels the same way about him, but they share a strong brother/best-friend relationship and show compassion and have each others' backs.
- Raphael - Donnie's second-oldest brother. He and Raph do fight occasionally, but tease and taunt each other more. Raph tends to tease and taunt Donnie about his "dorkiness" and smarts, while Donnie does the same to Raph about his "meatheadedness" and temper. Overall, they still have each others' backs and care about each other, as they are brothers, but they hardly show that kind of affection.
- Michelangelo- Donnie's younger brother. He and Mikey fight the most out of all his brothers, but they seem very close as brothers. Donnie tends to be the actual big brother to Mikey, whereas his other brothers just plan out what they're going to do, and just use Mikey as a sidekick. Donnie hates it whenever Mikey doesn't use his common sense or whenever he goofs off too much, but Donnie still loves him, as he is his little brother and best friend. Mikey, on the other hand, looks up to Donnie, and teases him about his huge crush on April, but he always tries helping Donnie, trying to impress him with his nunchuck skills.
- Splinter - Donnie's adoptive father and sensei. Donnie tries his best to listen to Splinter's advice, but most of Splinter's words tend to confuse him, which is ironic, because Donnie is NEVER confused once it comes to words. It is shown the Donnie questions Splinter's advice the MOST.
- April O'Neil - Donnie's best friend and crush. Donnie fell in love with April at first sight, despite her not noticing his immense attraction towards her. There are several episodes where Donnie actually shows his love for her, but he quickly takes it back, fearing that she'll not accept him and their friendship will go awry.
- Leatherhead - Donnie has neutral feelings about Leatherhead. While he see's him as a valuable ally, Donnie's very terrified of Leatherhead; mostly because there's a running gag where whenever Leatherhead looses control, he grabs Donnie by the face and shakes him like a rag doll. Leatherhead has regreted this action though and he see's Donnie as a good friend like he does all the turtles.
- Timothy (Pulverizer/Mutagen Man) - At first, Donnie wasn't sure whether or not to trust the Pulverizer in but as of the 22nd episode in the 1st season, Donnie finds out that his real name is Timothy. Timothy tries to mutate himself, hoping that he'll turn out to be like Donnie and his brothers. Fortunately, Donnie tries his best to stop him, warning Timothy that the mutagen is dangerous, and could even kill the Pulverizer if he put it on. Unfortunately, Timothy doesn't listen to him, and optimistically gets attacked by some mutagen. Donnie then promises that he'll find a cure for the Pulverizer.
- Karai - He is wary of Karai's tactics, and doesn't trust her at all, even though she offered to help him and his brothers with destroying the Kraang. Now, however, they are very close, considering the fact that they're both siblings.
- Rob Paulsen, who provides the voice for Donatello, also provided the voice of Raphael in the 1987 TV series until it's ninth season.
- Donatello's name is Italian, meaning "Gift Given from God". Given the fact that he was adopted by Hamato Yoshi/Splinter, Donatello's full name would be "Hamato Donatello".
- In Katakana, Donatello's name is spelt: ドナテッロ(Donaterro).
- Donatello is the tallest amongst his brothers, presumably at around 6 ft tall as seen on concept art of Pulverizer scale refers to the Turtles' maximum height.
- Donatello has a noticeable gap between his front teeth.
- In this incarnation, Donatello has a crush on April having fallen for her at first sight. In the 80s series, he was the only turtle not to have a significant crush on another character.
- While Donatello still fights with his weapons of choice, a Bō staff, in this incarnation his staff can be converted into Naginata, (a "pole-blade"), via a retractable blade inside one end of the staff. It has been seen as early as the events of I Think His Name is Baxter Stockman.
- In Metalhead, Donnie gets permission from Splinter to upgrade his weapon, but after the events of the episode, it would seem that he decided against it, but the retractable blade feature makes more appearances afterwards.
- Donnie is the first turtle other than Mikey to use the catchphrase "Booyakasha."
- Originally, Leatherhead would repeatedly grab Donatello's by the face and shake him around whenever he got enraged.
- Due to his behaviour in "I Think His Name Is Baxter Stockman" (and various other episodes), he is the second to Raphael in temper and anger.
- Despite being opposites, Donnie has been shown being really close to Mikey.
- When Donnie's T-Phone rings, it has the tune of the intro of the 1987 series.
- In Karai's Vendetta, his caller ID for April's phone is "Donny Boy" and she has a picture of him with flowers and stars, a dark red butterfly or bow on his mask and a silhouette of a cat.