Hannah Montana to Melrose Place (2009)

The same Obama impersonator from Hanna Montana was on I Didn't Do It

Trish and Dez from Austin & Ally appear in the Halloween episode of I Didn't Do It

Austin and Ally appear on an episode of Girl Meets World. Bringing the Disney Channel Live Action Universe into the Westphall Universe

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 Dr Turner was investigated for murder by Homicide's Pembleton and Bayliss.

Homicide's John Munch questioned The X-Files' The Lone Gunmen.

Brenda Walsh picks up a Morley smoking habit while in Paris on Beverly Hills 90210

90210 was a continuation of Beverly Hills 90210 years later

Melrose Place (2009) was a continuation of Melrose Place which was a spin off of Beverly Hills 90210 that was continued as 90210