This thread is dedicated to shows where the main character leaves, and is replaced by someone who isn't the main character. For example:

Richie Cunningham was the main character on “Happy Days.” Sure, Fonzie was more popular but Richie was the first billed, and when Richie ultimately left “Happy Days”, he was replaced by his cousin Roger, who was not the main character. Just one character of many.

Eric Forman was the main character on “That ‘70s Show.” When he left, however, his replacement, Randy Pearson, did not replace him as the main character, but simply became a member of the group.

Matt Garrison was the main character on “California Dreams.” When he left after the second season, the focus shifted more to Jake and Matt’s replacement, Mark, did not become the star of the show, but rather just another member of the band.

What are some others?

When John Travolta left Welcome Back Kotter he was replaced by Stephen Shortridge as Beau DeLabarre. Beau was one of the sweathogs but not their leader or star of the show. That role fell to Freddy "Boom Boom" Washington played by Lawrence-Hilton Jacobs.

when Valerie Harper quit "Valerie", they brought in Sandy Duncan, but the focus seemed to go more to Jason Bateman.

When Bea Benadaret, who played Kate Bradley on Petticoat Junction, passed away, she was replaced by June Lockhart as Dr. Janet Craig. Dr. Craig was a supporting character or at best part of the ensemble but certainly not the central character that Kate had been.

Reggie (Terry Farrell) was replaced by Chris (Nancy Travis) in the last season of Becker.

What about when Luke & Duke were replaced with Coy & Vance? :lol:

Or when they brought in that "biker chic" on Saved By The Bell to try and replace Kelly?

What about when Luke & Duke were replaced with Coy & Vance? :lol:

Or when they brought in that "biker chic" on Saved By The Bell to try and replace Kelly?

Forgot about Coy and Vance. Tori was the name of the biker chic on Saved By The Bell. She was played by Leanna Creel.

Another would be Edna Garrett (Charlotte Rae) being replaced by her sister Beverly Ann Stickle (Cloris Leachman) on The Facts of Life.

George Jefferson finally came and replaced his Brother Henry Jefferson on All In The Family, and wasn't seen again not even on The Jeffersons.

Shelley Long being replaced by Kirstie Alley.

How about these?

Fox Mulder (David Duchovny) is replaced by Robert Patrick on "X-Files".
Freddie Prinze replaced by the kid on "Chico and the Man".
Michael O'Hare (Jeffrey Sinclair) being replaced by Bruce Boxleitner (John Sheridan) on "Babylon 5".
Gareth Thomas (Blake) on "Blakes7" replaced by Stephen Pacey (Tarrant).

Don Knotts, Barney Fife on The Andy Griffith Show and a key character, was replaced briefly by Jack Burns, who played Deputy Warren Ferguson (after Knotts left the series). But there was no replacing such a unique character, so aside from Knotts' guest-starring return episodes, the void remained once Burns' character exited.

Gale Gordon replacing Joseph Kerns on "Dennis the Menace" after Joseph Kerns died.

Then there are Ted McGinley who replaced David Garrison on Married With Children.

Tiffani Amber Thiessen replacing Shannen Doherty on Beverly Hills 90210.