"Diamond" Joe Quimby (voiced by Dan Castellaneta) is a fictional character featured in The Simpsons animated series. He has long served as the Mayor of the fictional city of Springfield, and appears to be a slick, sleazy politician whose only interest lies in staying in power for the fringe benefits it brings. Those benefits apparently include large numbers of nubile young women. He speaks with a Bostonian accent which resembles that of John F. Kennedy.

Assisted by his equally slick and sleazy aides, Joe can be expected to turn up at any public event and promise exactly what the audience wants to hear. For instance, after discovering that the only thing that interests the residents of the Springfield Retirement Home is Matlock (a TV detective series that ran between 1986 and 1995), he promptly decides to name a new freeway the "Matlock Expressway". He is also known to be a womanizer and to occasionally amuse himself with pornographic playing cards during particularly boring town meetings.

It has been implied on occasion that Joe is connected to Fat Tony, the local Mafia Don.

See also : The Simpsons