What star? Shows that survived major cast changes and kept going

In 1994, Michael Moriarty left "Law & Order" after a showdown with U.S. Attorney General Janet Reno, who had criticized the show’s violent content. Moriarty claims he was pushed out; producers say his behavior became erratic, and he was written out of the show. At the time, people wondered if "Law & Order" could survive a cast change, not realizing that cast turnover would become a hallmark of the show. Sam Waterston replaced Moriarty and continued as the assistant district attorney for 16 seasons, lasting long enough for his character to get promoted to DA. Meanwhile, Moriarty declared himself a political exile, moved to Canada and later won an Emmy for playing James Dean's father.

"NYPD Blue" was originally a vehicle for David Caruso's detective John Kelly, but Caruso left the show early in the second season when he couldn't get a raise, as well as a 38-foot trailer, his own development executive and Fridays off. Jimmy Smits replaced Caruso and left after Season 6. The show lasted a full 12 seasons, even with Mark-Paul Gosselaar and Rick "Don't Call Me Ricky" Schroder, which is a testament to the talents of Dennis “Sipowicz” Franz, who doesn’t do commercials! Caruso and his sunglasses returned to television eight years later as the star of "CSI: Miami."

Valerie Harper's departure from "Valerie" proved that having your name in the title doesn't guarantee job security. When Harper and her producer husband held out after two seasons, NBC fired her and replaced her with Sandy Duncan. The character of Valerie was killed off, and the show became "Valerie's Family" and then "The Hogan Family." The show ran four more years, thanks to Duncan and emerging star Jason Bateman, while Harper won a $1.8 million settlement for breach of contract.

In 1987, Shelley Long had played Diane Chambers for five seasons on "Cheers." She'd won an Emmy, and earlier that year she had a hit movie with Bette Midler called "Outrageous Fortune." She decided to leave and pursue a movie career, which didn't work out well, but replacing her with Kirstie Alley worked out great for the show. Free from the Sam-Diane storyline, which had run its course after five years, the ensemble thrived, and Alley brought a madcap energy to the role of Rebecca Howe. The show went 11 seasons and ended up with more Rebecca episodes than Diane episodes (149-124).

In his return to television after "The King of Queens," Kevin James was doing pretty well with "Kevin Can Wait," which was a respectable No. 32 in the ratings. However, once his "Queens" co-star Leah Remini guest-starred at the end of Season One, the producers made a bold decision: kill off Kevin's wife, played by Erinn Hayes, so James could pair with his old co-star. Not only did they kill off Kevin's wife off, they spent less than a minute discussing her death. This may have alienated viewers, as "Kevin Can Wait" itself was killed off by CBS less than a year later. 

After eight seasons of shooting "The Walking Dead" in Georgia, Andrew Lincoln, who played the show's protagonist, Rick Grimes, wanted to spend more time with his family in England. So in Season Nine, Grimes blew up a bridge and was presumed dead – though viewers saw him rescued by a helicopter, so he could later star in three planned Rick Grimes movies. Perhaps the sheer number of characters already killed off on the show makes it easier to learn the main character, or that Grimes is dead in the comic book source material. Regardless, with one spinoff show already, three future Grimes movies, and even more spinoffs in development, Walking Dead fans have as much content as they want. Besides, aren't the zombies the real main characters?

McLean Stevenson asked out of his contract on MASH after three seasons because he didn’t like playing a supporting role to Alan Alda. Of course, he later realized that while he thought audiences loved McLean Stevenson, it turned out they really liked the character of Col. Henry Blake. Wayne Rogers also asked out of the role of Trapper John after three seasons; MASH ran eight more seasons without him, and spinoff "Trapper John M.D." ran seven, also without him.

"Roseanne" changed Beckys when Lecy Goranson enrolled at Vassar. She spent a season appearing sparingly, mostly on the phone, before Sarah Chalke replaced her for Seasons 6 and 7. Then in Season 8, Goranson returned but had to leave again, so half the episodes had Chalke as Becky and then Season 9 was all Chalke. In the reboot, Goranson returns as Becky, but Chalke also has a part as a woman named Andrea who hires Becky as her surrogate. Of course, now "The Conners" is going to continue without Roseanne herself, who was killed off by an opioid overdose, possibly after posting a bunch of racist tweets.

John Ritter experienced heart problems while rehearsing for the second season of "8 Simple Rules For Dating My Teenage Daughter," and after being misdiagnosed as having a heart attack, died during surgery. After a hiatus, the show continued, with Katey Sagal introducing the three completed episodes with Ritter and the addition of James Garner and David Spade to the cast. The series, retitled "8 Simple Rules," still lasted three seasons, but ABC canceled it due to declining ratings and pessimism about its syndication prospects.

Steve Carell was cast as Michael Scott in the American remake of "The Office," which premiered in March of 2005. By the fall of 2005, "The 40-Year-Old Virgin" had made Carell a movie star, but he was under contract for the next six years. Carell made the most of his time, writing and directing multiple episodes while garnering six Emmy nominations (somehow never winning!). The show never quite recovered from his departure, bringing in James Spader and focusing on Ed Helms' wildly unlikable Andy Bernard. Still, they made it two more seasons and delivered a satisfying series finale, featuring the inevitable-in-hindsight triumph of Dwight Schrute.

Though she's the most famous of all the angels, Farrah Fawcett was in only 29 episodes of "Charlie's Angels."   According to producer Aaron Spelling, she was in breach of her contract. After being threatened with a lawsuit, Fawcett agreed to make guest appearances on the third and fourth seasons of the show, while she was replaced in the title trio by Cheryl Ladd. Fawcett really did become a serious actress, winning acclaim for her theater work and earning six Golden Globe nominations. The show also ran two seasons after the departure of Kate Jackson, who left after three years, in part because the producers refused to let her do "Kramer vs. Kramer," in the role for which Meryl Streep won an Oscar.

Suzanne Somers was three seasons into "Three's Company" when she incurred the wrath of the show's producers. Her crime? Asking to be paid the same as co-star John Ritter. As a result, Somers appeared in only 60 seconds of each episode of the fourth season and was ultimately replaced by her character's cousin. Somers' career went into a tailspin until her '90s comeback, starring in "Step By Step" and selling Thighmasters.

Four seasons into its run, health issues forced Michael J. Fox to leave "Spin City." The show had already added Heather Locklear to reduce Fox's workload in Season 4, but in Season 5 Charlie Sheen was added to stabilize the show. Yes, there was a time when Charlie Sheen was considered a stabilizing force. The show also lost Connie Britton that year, and honestly, when Connie Britton leaves you might as well cancel your show. But "Spin City" made it through six seasons all the same.

From replacement to replaced. Charlie Sheen was making over a million dollars per episode on "Two And A Half Men," but his struggles with addiction forced the show to go on hiatus in the seventh season. The next year, Sheen trashed a hotel room, went in and out of rehab and publicly trashed show creator Chuck Lorre while also declaring he had "tiger blood." Ashton Kutcher replaced Sheen for the final four seasons, making his first appearance in a cloud of Sheen's character's ashes. The show also lost its half-man, Angus Jones, after he converted to Christianity and decided it was "filth that contradicts his moral values." But the show kept going for two two-man-only seasons. 

William Hartnell was the original "Doctor Who" on the BBC but suffered from arteriosclerosis, which affected his health and his ability to learn his lines. When it became clear he couldn’t continue, producers came up with the audacious idea that the alien Time Lord could simply “regenerate” and change his appearance. Since then, there have been 12 other Doctors Who in the subsequent 52 years. The only truly consistent thing about "Doctor Who" is its refusal to spend more than $15 per episode on special effects.

"A Different World" was originally conceived as a star vehicle for "Cosby Show" star Lisa Bonet. But before that, it was actually a vehicle for Meg Ryan, who would have played a white girl attending a historically black college. (This role would probably go to Scarlett Johansson today.) When Bonet got pregnant after Season One, she and Marisa Tomei, playing Denise Huxtable’s white roommate, left the cast, Debbie Allen took over as showrunner, and the show became much more about the HBCU experience. It ran five more seasons and focused on Jasmine Guy's Whitley Gilbert and eyewear pioneer Dwayne Wayne.

At the beginning of the third season of "Criminal Minds," lead actor Mandy Patinkin suddenly quit the show, citing the brutality of its content. Replacement Joe Mantegna hasn’t minded solving serial murders every week and spent 13 seasons as head of the BAU. There was some shuffling of the cast over the show’s 15 seasons, including Thomas Gibson’s departure in Season 12 after reportedly kicking a producer. But it's been a remarkably consistent ensemble for a show that lasted for a decade and a half.

The show lost Shannen Doherty after four seasons, Luke Perry left after Season 6, and Jason Priestley lasted only four episodes into Season 9. It turns out it was a show about Tori Spelling's character the whole time! Donna Martin graduates! Priestley says he still regrets leaving before the series concluded, Doherty got fired for tardiness, and Perry came back after a three-year absence when his expected movie career didn’t happen. Doherty did return for a few appearances on the spinoff, "90210," which ran for over 100 episodes.

After seven seasons of "The X-Files," David Duchovny sued Fox after the network sold rights to the show to its own subsidiaries, for a discounted price. That reduced Duchovny’s cut of the sale, while Fox appeased creator Chris Carter by ordering a new series from him. Yes, it was an "X-Files" conspiracy that turned out to be true, and Fox eventually settled for $20 million. As a result, Fox Mulder was abducted by aliens, Duchovny appeared in only half of Season 8’s episodes, and Robert “T1000” Patrick took over the lead role. Gillian Anderson stepped back the next year, and Season 9 happened with Patrick and Annabeth Gish as the leads. Duchovny and Anderson returned as Mulder and Scully in a 2008 feature film plus short-series revivals in 2016 and 2018.

After 13 years, the original Tom Barnaby, John Nettles, had had enough with the violence and death in the sprawling fictional Midsomer County. So producers brought in Neil Dudgeon as Barnaby’s cousin, detective chief inspector John Barnaby, and the Midsomer bloodshed has continued for ten seasons and counting. The partners come and go, but as long as there’s a Barnaby in charge of solving the many, many crimes, no one is safe from murder by pitchfork, croquet hook, electrified exercise bike or wheel of cheese.

Originally, "Saved By The Bell" was a Disney channel sitcom called "Good Morning, Miss Bliss," starring former parent trapper Hayley Mills as an eighth-grade teacher. But after one season, the show dropped Mills and moved the students and Principal Belding to a high school in California. Later, the show lost Elizabeth Berkley and Tiffani-Amber Thiessen in the final season and rolled with the wildly unpopular Tori for the show’s last episodes. The most consistent cast member was Dennis Haskins, who thanks to "Saved By The Bell: The New Class" ended up playing Mr. Belding for 12 straight years.

William Peterson left "CSI" in 2009, probably because nine years of finding disgusting fluids with a black light is enough for any person. The show brought in Laurence Fishburne to replace him and then Ted Danson to replace Fishburne for the final four seasons. Because who else could replace Morpheus but Sam Malone?

Robin Wright's Claire Underwood took over as POTUS at the end of Season Five of "House of Cards," and took over as the show's solo lead for its final season. The disgraced Frank Underwood was killing off between seasons after the disgraced Kevin Spacey was fired off the show. It wasn't unprecedented, given the show killed off Kate Mara's character early in Season Two. They filled out the cast for the final season by adding Diane Lane and greg Kinnear. Somehow the terrible things Underwood did over five seasons don't seem that bad compared to what Spacey did in real life.