Off the top of my head, in no particular order: Seinfeld, Friends, Malcolm in the Middle, Arrested Development, the Simpsons, Leave It To Beaver, King of the Hill, Happy Days, Sanford and Son, All in the Family.
I feel like I'm forgetting something obvious. Oh well. Honorary mention to the Beverly Hillbillies and Three's Company.
I wouldn't classify most animated series as sitcoms, otherwise I'd have to include more of them, particularly Beavis and Butthead and South Park. Simpsons and King of the Hill seem to fit the sitcom format more precisely, for some reason. I'm on the fence as to whether or not Family Guy counts; if so, I'll add it to the list.