Mutant Nurse

Down in the sewers beneath New New York, where the city's mutants live hidden from the surface world, the Mutant Nurse tends to her own kind with brisk, no-nonsense care. She's practical and unsentimental, a quiet fixture of an underground society most Futurama characters never think to look for.

She's a small piece of Futurama's trick of building whole hidden worlds out of a single throwaway joke, and Tress MacNeille gives her just enough dry, weary warmth to feel like a real person with a real job rather than a punchline. The character sticks precisely because the show never overexplains her.