Harold "Bill" "Scott"Reginald is a background ratfish who first appears in the episode "Ripped Pants." Like other character models, his appearance is not perfectly consistent, and in some episodes, he is completely naked.
He is a light blue fish with a dark blue dorsal fin. On the sides of his head, there are light red-purple spots. He has light salmon lips and black eyes. He wears a white t-shirt and a red speedo. In some episodes, he speaks with an Australian accent.
He appears to be ill-tempered and cynical in most of his appearances. His name is revealed in the episode "Roller Cowards." In "Porous Pockets," Bert calls him "Bill." However, his name is confirmed in "Gary in Love" as "Harold."
He has been voiced by both Doug Lawrence and Dee Bradley Baker. Lawrence's portrayal gives him a more common American accent, while Baker's gives him an English one.