Homer's father
Abraham Simpson (voiced by [Dan Castellaneta]
?), an ancient, grizzled figure, lives in the Springfield Retirement Home, a sad, lonely place filled with demented, crippled, and depressed old people (a sign near the entrance says "Thank you for not mentioning the outside world"). Bart and Lisa greatly fear his occasional childminding sessions--at least until he falls asleep and leaves them to their own devices. In the meantime he fills his time with complaining about anything and everything to anyone and everyone he can find.
See: The Simpsons/Characters