Donatello and his four brothers were ordinary turtles before getting covered in mutagen which would transform them into humanoid turtles. Donatello was given a purple mask, wields a bo-staff and is the brains of the team, helping develop tech for the missions of the TMNT.
Due to the fact that the Teenage Mutant Ninja Turtles appeared in a specific order as they all fought each other in a Battle Royale, this means that Donatello is the seventh character to appear on Death Battle who first came to being in the 1980s era. In his case being 1984 as he among his three other brothers first came to being in the comics. The last six characters that appeared on Death Battle who first came to being within the 1980s era where Leonardo, Mike Haggar, Goomba, Koopa Troopa, Rogue and Samus Aran.