NBC just did a piece on Joey from Friends upcoming spin-off. and touched on some other shows that were spun off that i forgot about or didn’t know.
All In The Family begat Maude, Good Times and The Jeffersons
Happy Days begat Laverne and Shirley, Mork and Mindy and Joannie Love Chachi
Perfect Strangers begat Family Matters (around Harriet the elevator operator)
and a few obvious others like Mary Tyler Moore and Cheers