Derek Nefaidos is an american voice actor, for Fireboy & Watergirl.
- Waterboy - a main character, who is Watergirl's younger brother
- ZungBoy - a supporting character, Fireboy and Watergirl's good friend, and BlackGirl's boyfriend
- Male Programming Computers - minor characters, computers at Programming Working Space, who are capable of speaking
- Sheep Man - a minor character, who is a middle-aged sheep man