Donatello wears a purple mask in the Teenage Mutant Ninja Turtles franchise.
The color-coding system helps audiences distinguish the four brothers, especially in animated productions and merchandise. Donatello is generally portrayed as the team’s inventor and technical expert, and his signature weapon is the bo staff. Purple therefore became strongly associated with his visual identity.
The turtles were not always color-coded in exactly the same way. In the earliest black-and-white Mirage comics, all four brothers wore red masks, making their weapons and dialogue more important for identification. The different mask colors became especially prominent in the 1987 animated series and many later adaptations.
Donatello is named after the Italian Renaissance sculptor Donatello. His name is often shortened to Donnie in dialogue. The purple mask belongs to Donatello; Michelangelo’s orange mask, Raphael’s red mask, and Leonardo’s blue mask identify his brothers.