Can you think of any?

On Dennis the Menace the actor who played Mr. Wilson died. I believe after his death the show only went on for one more season with a different Mr. Wilson who was suppose to be his brother.

On the Facts of Life, during the last two seasons Mrs. Garrett leaves the show for good and is replaced with her sister.

Dick York replaced by Dick Sargent on Bewitched. Dick York was the best.
Most of us know what took place on Three's Company with the Ropers and Christmas Snow.

One example that immediately came to my mind upon seeing the name of this topic involved the actor who originally played the character Harriette Winslow on the TV program "Family Matters" (JoMarie Payton was her name) being replaced for its final series of episodes (Judyann Elder was the name of the actor who replaced JoMarie Payton) .

One example that immediately came to my mind upon seeing the name of this topic involved the actor who originally played the character Harriette Winslow on the TV program "Family Matters" (JoMarie Payton was her name) being replaced for its final series of episodes (Judyann Elder was the name of the actor who replaced JoMarie Payton) .
No offense to either actress that played Hariette but I wish the original (Payton) would've stayed for the last few episodes. By her leaving, it ruined the legacy of the show, IMO. Although, the legacy was ruined long before when they forgot about Judy.

Dick York replaced by Dick Sargent on Bewitched. Dick York was the best.
Most of us know what took place on Three's Company with the Ropers and Christmas Snow.
I don't know; what happened?

I don't know; what happened?

Chrissy left because Suzanne Somers made some outrageous demands. The Ropers left to do a spin-off series.

On The Office, Steve Carell departed the series at the end of its seventh season. The show lasted two seasons without Michael Scott. Ed Helms' character, Andy Bernard took over as Regional Manager for those seasons.

On NewsRadio, Phil Hartman (who played Bill McNeal) was murdered after completing the fourth season. The show ran for one more season with Jon Lovitz (playing Max Louis) taking his place.

On Laverne & Shirley, Cindy Williams (Shirley) left the show two episodes into the 8th season. The show finished out that season before finally going off the air for good. Although word has it, ABC wanted more but Penny Marshall said no.

On That '70s Show, Topher Grace and Ashton Kutcher both announced they were leaving at the end of the seventh season. As it happened, Kutcher stayed on for a few episodes as a guest star before departing. The eighth season would be the last, so in the end, there's only one season without Foreman.

I can think of more but I'll give other people a chance to name some. ;)