Cassius is Dexter's disgruntled talking pigeon who's in charge of managing his super secret Sky Port, an occupation which Dee Dee finds quite ridiculous. He was seen in the episode "The Continuum of Cartoon Fools" where he was forced by Dexter to take Dee Dee out via the emergency exit in the Sky Port. The struggling pigeon then merely uttered "It's a living". He was voiced by Jeff Bennett.
- The fact that he speaks and his comment of "It's a living" over his ridiculous occupation is a reference to the animal appliances from The Flintstones who would often comment on their rather unfortunate occupations.