Mayberry R.F.D. to The City

was a spin off of The Andy Griffith Show

Gomer Pyle, U.S.M.C was a spin off of The Andy Griffith Show

The Lucy Show's Lucy Carmichael was accidentally drafted into Gomer Pyle, USMC's company on an episode of The Lucy Show.

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

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.

Diagnosis Murder's Dr Mark Sloan was defended by Matlock when Sloan was accused of murder

All My Children and Loving feature the fictional Trans Global Airlines

All My Children and Loving crossed over a number of times.

The City spun off of Loving survivors of the Corinth Serial Killer leave Corinth to an apartment building in NY SoHo