Hanging In to The Lucy Show

Hanging In (and Maude's) Maggie Gallagher crossed over onto Soap for 10 episode

The first All in the Family spinoff character was Maude. Maude was Edith Bunker's cousin.

The Jeffersons' George Jefferson was the second All in the Family supporting character to spinoff onto his own show.

George Jefferson gets help from Barney Collier from Mission Impossible

Mission: Impossible was continued 22 years later

Characters from Mission: Impossible were also featured on an episode of Here's Lucy.

Here's Lucy's Mary Jane Lewis was originally a character on The Lucy Show (also called The Lucille Ball Show).