The later-created "Mad About You" was not a spinoff of "Seinfeld," but they certainly ran in the same circles.

In 1990 NBC launched "Seinfeld," a sitcom starring comedian Jerry Seinfeld, about life in New York City and based on parts of his previous stand-up routine. 

Two years later, in the slot right after "Seinfeld," NBC launched "Mad About You," a sitcom starring comedian Paul Reiser, about life in New York City and based on parts of his previous stand-up routine.

A link was inevitable.

It happened early in "Mad About You's" first season - the eighth episode, to be exact -- in an episode called "The Apartment." In it, Jamie finds out that Paul has been subletting his previous apartment since they moved in together and she demands he gives the lease to its oddball tenant, Cosmo Kramer.

The move was likely a play to boost the fledgling show's ratings by tying it to an established hit.

The connection continued on the other side as well. In an episode of "Seinfeld," George complains about the fact that his girlfriend Susan is always making him watch "Mad About You."

And Seinfeld himself appeared in the seventh season premiere of "Mad About You," a few months after his series left the air.

Both series enjoyed long runs on NBC, with "Mad About You" signing off in 1999, one season after "Seinfeld" did.