Seth Green (born Seth Benjamin Gesshel-Green on February 8, 1974; 45 years old) is an American actor and voice actor best known for his work on Robot Chicken and Family Guy.
Seth Green played the role with a very noticeably different vocal timbre than either Biggs or Catrambone, who had actually sounded more similar to each other than either did to Green. In, Within the Woods, Green's first episode as Leonardo, the change in the sound of Leo's voice is explained by Donatello as Leo having sustained damage to his throat. The fact that Leonardo had been recast was further lampshaded during the episode, such as when the still seriously injured Leo says, "I don't think I'll ever be the same," and Raphael responds, "Don't talk like that, that's not the Leo I know!"
- Green took the role because his wife's favorite Turtle is Leonardo, and he wanted to play a character his wife already had "the hots for." At this, Rob Paulsen said that it was "very convenient."