He's big, he's green, and he's stupid.  He swims, he eats, and he burps.  He's Dopefish, a beloved character from the classic PC game Commander Keen: Goodbye Galaxy!  Dopefish appears in the Well Of Wishes level and pursues the swimming Commander Keen with the intent of swallowing the lad whole.  According to Keen lore, Dopefish's thought pattern is a never-ending refrain of "Swim, swim, hungry; swim, swim, hungry".  You've problem come across him before, but you just never knew it.  Fans of the beloved character keep a vigil at Dopefish.com where every official appearance and cameo of the character is noted and cataloged (with screenshots!).

Dopefish is the product of the fertile mind of Tom Hall. It was one of 24 drawings he did of ideas for characters for Commander Keen: Goodbye, Galaxy! while part of id Software. Dopefish was one of the characters from these drawings that made the cut. According to Tom, "I just drew this stupid little fish," and the rest is history.

Dopefish Mania soon followed as the character popped up in games such as Wacky Wheels, Duke Nukem 3D (as a hidden text message), Quake II, and even Max Payne.  Dopefish has gone silent recently, but rest assured that if Commander Keen ever returns, Dopefish will be there right along with him (trying to eat our hero, no doubt).