Computress is a living computer who only appeared in the episode Dexter and Computress Get Mandark!. He is Mandark's "brother". The character was created by six and half year-old Tyler Samuel Lee who won a special contest on Cartoon Network to write an episode of Dexter's Laboratory.
Originally Mandark's brother, Computress was hated by him for destroying his laboratory and was later kicked out. Dexter then teams up with Computress to get revenge on Mandark for mistreating him. Shortly after Mandark's defeat, Dexter chastises Computress for what he did, making Computress walk away with his head lowered.