Leg Mutant

Leg Mutant is exactly what the name promises: one of the many deformed sewer-dwellers living beneath New New York, glimpsed among the outcasts who've been driven underground by a society that shuns mutants. He shuffles through background scenes, extra limbs and all, part of the city's hidden, unglamorous underclass.

Futurama's throwaway mutants are where the show quietly does its best world-building, and Leg Mutant is a fine example — a sight gag with a name, existing mostly to make the sewers feel populated and strange. David Herman gives him just enough voice to land a passing line, proof that even a joke can carry a flicker of personality.