Mister Ed to Touched by an Angel

Hi Honey, I'm Home!'s Lloyd was friends with Mister Ed

Alice & Trixie from The Honeymooners crossed over onto Hi Honey, I'm Home!

Here's Lucy's Lucy was driven around Miami by Ralph Cramden of The Hooneymooner's

Here's Lucy's Lucy Carter and Mannix's Mannix are held hostage in an episode of Here's Lucy.

Mannix returned to TV on an episode of Diagnosis Murder to solve an old unsolved case with the help of Dr Mark Sloan.

Promised Land's Russell Greene helped his boss Ryan Matthews face his families past, then Ryan crossed-over onto Diagnosis Murder to ID the body of one of his ex-wife's old friends

Promised Land was a spinoff of Touched By an Angel.