Liv and Maddie to Seinfeld

Cyd and Shelby from Best Friends Whenever appear on a Halloween episode of Liv and Maddie

Riley and Lucas from Girl Meets World appear in the Halloween episode of Best Friends Whenever

Continuation of Boy Meets Wolrd

Sabrina the Teenage Witch also crossed over with Boy Meets World on several other occasions.

Sabrina from Sabrina the Teenage Witch visited Cher from Clueless in the episode "Mr. Wright."

Hakeem and Niecy from Moesha went to the prom with Cher and Sean from Clueless.

The Parkers was a spinoff of Moesha

The Hughleys crossed over with The Parkers.

The Drew Carey Show's Mimi appeared in an episode of The Hughleys

The Drew Carey Show did a cross over with Coach.

Newhart's Larry, Darryl and Darryl squatted in Coach's Hayden and Christine's home

The Bob Newhart Show's Bob Hartley woke up after dreaming the entire series Newhart during Newhart's finale.

The Bob Newhart Show's Elliot Carlin visited the psych ward at St Elsewhere's St Eligius Hospital.

St Elsewhere's Westphall, Craig and Auschlander visited Cheers' bar

Cheers spun-off Frasier

Fraiser's Niles and Daphne read Caroline in the City's comic strip.

Caroline in the City's Caroline wished The Single Guy's Jonathan good luck

Friends was affected by the blackout created by Mad About You's Jamie on Blackout Thursday.

Mad About You's Paul leased his old apartment to Seinfeld's Kramer.