Under normal circumstances, the maincharacters of TV showsremain relevantly consistent, although there are some series that have consistently shaken things up. From behind-the-scenes controversies to character arcs simply running their course, new characters and recastings are sometimes inevitable, but they can be difficult for viewers who have grown attached to their favorite cast members to get used to. While sometimes theintroduction of new main charactersfeels fresh and exciting, other times it signals the beginning of the end as a series kisses goodbye to its glory days.
Character changes occur in everything from beloved sitcoms to prestige dramas, and many of thebest shows of all timehave switched out main characters for new cast members. In some instances, even theprotagonists of TV series have exited and were quickly replaced by somebody new. Several long-running series even had main character changes built into their very nature asDoctors regenerate, Queens move into new periods of their lives, or medical teams disband.
8Two And A Half Men (2003 - 2015)
Two and a Half Men replaced Charlie Sheen
The CBS sitcomTwo and a Half Menwas originally based on the hedonistic bachelor Charlie Harper’s life being turned upside downafter his brother Alan and 10-year-old nephew Jake move in with him. Taking influence from its star Charlie Sheen’s real-life womanizing, everything aboutTwo and a Half Meninitially revolves around Charlie’s reaction and frustration as his newly arrived family intrudes on his life of casual sexual misadventures. With Alan acting as a total contrast to Charlie’s unrestrained behavior, the opposing siblings' dynamic was what drove much of the humor in the show.
However, behind-the-scenes controversies led to Sheen exiting the show due to a substance abuse issue and a public spat with the series creator, Chuck Lorre, which meant his contract was terminated during the eighth season. This led to Ashton Kutcher being brought in to replace Sheen as the new billionaire character, Walden Schmidt, who bought Harper’s home and inexplicably allowed Alan to continue living with him. With Jake’s role also significantly reduced, this major cast change shook up the dynamic ofTwo and a Half Menfor its remaining four seasons.
Two and a Half Men
Cast
Two and a Half Men follows the Harper family: Charlie (Charlie Sheen), a womanizing, hedonistic jingle writer who enjoys his lazy lifestyle from the comfort of his large beach house; Alan (Jon Cryer), Charlie’s neurotic, far less successful brother; and Jake (Angus T. Jones), Alan’s impressionable son. When Alan’s marriage falls apart, he moves in with Charlie, much to the older brother’s dismay. After bonding with his nephew, Charlie reluctantly embraces Alan’s presence, paving the way for one of television’s most dysfunctional family environments.
7Parks And Recreation (2009 - 2015)
Parks and Recreation featured major character shifts in season 3
Parks and Recreationfeatured one of the best ensemble casts in sitcom history as the comedic talents of Amy Poehler, Nick Offerman, and Aubrey Plaza made this NBC series a major hit. However, it wasn’t always this way, as the first season ofParks and Recstruggled to find its feet, and major character shifts occurred right up until the third season. One prime example of this was Paul Schneider as Mark Brendanawicz, the jaded city planner whose character never fully fit in and who left the series at the end of season 2, never to be mentioned again.
Schneider’s absence left a gap inParks and Recthat was thankfully filled by Adam Scott as Ben Wyatt and Rob Lowe as Chris Traeger, two characters who previously appeared in guest roles. Scott and Lowe were the magic missing ingredient, and their hilarious dynamic and unique sense of humor fit right in, with Ben acting as a major love interest for Leslie and Chris becoming the boyfriend of Rashida Jones’ Ann Perkins. As two of the show’s best characters, the introduction of Ben and Chris showcased that it’s never too late to add to a sitcom’s ensemble cast.
Parks and Recreation
Parks and Recreation is a television series that premiered in 2009, focusing on Leslie Knope, a mid-level bureaucrat in Pawnee, Indiana. She encounters various challenges from bureaucrats and citizens while striving to beautify the town through her role in the Parks and Recreation Department.
In a post-apocalyptic world that’s been ravaged by zombies, it’s no surprise thatThe Walking Deadhad its fair share of dramatic character exits and entrances. Within a kill-or-be-killed society, life is often brutish, nasty, and short, as survivors must do anything in their power to stay alive and protect the ones that they love. While there were plenty of consistent characters, such as Andrew Lincoln’s Rick Grimes,part of the thrill of watchingThe Walking Deadwas never being certain who would live or diefrom one week to the next.
The Walking Deadalso consistently introduced new foes and threats, and terrifying villains like David Morrissey as The Governor or Jeffrey Dean Morgan as Negan kept things frighteningly interesting. The main protagonists were not even assured to stick around, as Rick exited the show during the 9th season. However, this wasn’t the end for Rick’s character, who returned in the spin-off seriesThe Walking Dead: The Ones Who Live, which was just one of many offshoots within this sprawling zombie franchise.
The Walking Dead
The Walking Dead is a television series that premiered on July 24, 2025. It follows Sheriff’s deputy Rick Grimes, who awakens from a coma to find a post-apocalyptic world overrun by zombies. He embarks on a journey to locate his family, encountering various survivors amidst the chaos.
5CSI: Crime Scene Investigation (2000 - 2015)
WhileCSIwas a major hit for CBS, it garnered some of the network’s biggest ratings and became a total cultural phenomenon. It alsofeatured many major cast changes throughout its 15-season run. Focusing on a team of crime scene investigators solving murders for the Las Vegas Police Department, the longevity of the show meant that many characters came and went. WhileCSIwas led by William Petersen as the forensic analyst Gil Grissom for its first nine seasons, even this main protagonist was not part of the show for its entirety.
Plenty ofactors leftCSIbefore it ended, as Petersen decided nine years with the show was enough, and characters like Warrick Brown were killed off at the end of season 8. However, these major exits opened the door for major names like Laurence Fishburne to fill their gap as he briefly joined the main cast from season nine through to eleven. As a sprawling series with 337 episodes, it’s no surprise that plenty of main characters came and went across the fifteen years the show was on the air.
CSI: Crime Scene Investigation
CSI: Crime Scene Investigation centers around a team of forensic investigators in Las Vegas. The series, released in 2000, follows the experts as they solve criminal cases by meticulously analyzing crime scenes, gathering evidence, and uncovering the truth behind various mysteries.
4The Thick Of It (2005 - 2012)
The Thick of It saw a major cast shift due to behind-the-scenes controversy
Before gaining recognition in the US for his hilarious political satireVeepon HBO, Armando Iannucci was behind some of the funniest series on British television, likeThe Thick of It. This outrageous comedy showcased the inner workings of the British government and the chaotic goings-on of politicians, spin doctors, journalists, and advisors. While characters such as Peter Capaldi’s foul-mouthed director of communications, Malcolm Tucker, were consistent throughout, a behind-the-scenes controversy led to a major reshuffling of the main cast.
The Thick of Itoriginally starred Chris Langham as the hapless MP Hugh Abbot, a politician totally out of touch with the general public, who exited the show after series two due to a conviction for downloading child pornography (viaGuardian.) This controversial and sudden exit meant new characters, such as Rebecca Front, asthe newly appointed MP Nicola Murray. Front was already a major name in British comedy with a longstanding creative relationship with Armando, and having already appeared in everything fromThe Day TodaytoKnowing Me Knowing You with Alan Partridge, she fit right in.
The Thick Of It
The Thick of It is a British political satire television series created by Armando Iannucci. Premiering in 2005, the show offers a behind-the-scenes look at the often chaotic workings of government through the eyes of its characters, including the formidable spin doctor Malcolm Tucker, portrayed by Peter Capaldi. The series is known for its sharp wit, fast-paced dialogue, and biting commentary on modern politics.
3House (2004 - 2012)
House’s core team of medical experts shifted throughout the show’s run
The medical dramaHousefeatured Hugh Laurie and the titular genius misanthrope, Dr. Gregory House, throughout its eight-season run. With a talented supporting ensemble cast that included Dr. House’s one true friend, Dr. James Wilson, and his Dean of Medicine and eventual love interest, Dr. Lisa Cuddy, this procedural series was packed with intrigue as House endeavored to solve a complex medical mystery every week. Another major component ofHousewas his diagnostic team, which shifted and changed throughout the show’s run.
While the first three seasons ofHousesaw the notorious doctor consistently accompanied by Dr. Robert Chase (Jesse Spencer), Dr. Allison Cameron (Jennifer Morrison), and Dr. Eric Foreman (Omar Epps), following that season, this team disbanded. That led to the introduction of new main characters, such as Olivia Wilde as Thirteen or Kal Penn as Dr. Kutner, new medical voices who helped keep the show feeling new and fresh throughout its run. WhileHousehad plenty of character changes over the course of its run, it also felt natural and aligned with the shifting roles of medical practitioners.
House
House is a medical mystery drama in which the villain is typically a difficult-to-diagnose medical malady. It follows Dr. Gregory House (Hugh Laurie), a world-renowned disabled diagnostician with a notorious substance abuse issue. With his team of world-class doctors, House has built a reputation as one of the most brilliant doctors in the world - an especially impressive feat when taking into account that he rarely actually sees his patients.
2The Crown (2016 - 2023)
The Crown changed its entire main cast every two seasons
The Netflix historical dramaThe Crowndepicts the history of the British royal family, starting just before the reign of Queen Elizabeth II and going through modern times. As an incredibly ambitious series that viewers through everything from the post-WWII era right through to media fascination with figures like Princess Diana and Kate Middleton,the sprawling nature ofThe Crownmeant that its actors were continually recastwith new actors every two seasons. This saw Claire Foy, Olivia Colman, and Imelda Staunton all portraying the Queen at different points in her life.
The shifting cast ofThe Crownwas a bold decision, as Claire Foy did such an excellent job embodying the young Queen that it was sad to see her go. However, the show had such strong writing, high production values, and an intense commitment from its ensemble cast that although it took a while to get used to the new cast, each generation added something unique to the series. While many will bicker over which era ofThe Crownhad the best cast, that did not stop it from remaining one of Netflix’s most popular shows throughout its six-season run.
The Crown
The Crown is a Netflix Historical Drama created by Peter Morgan and starring Claire Foy, Olivia Colman, and Imelda Staunton. The series follows the life of ruler Queen Elizabeth II, outlining different points in her life.
1Doctor Who (1963 - Present)
Doctor Who’s title character regenerates to allow a new actor to take their place
WhenDoctor Whofirst premiered in 1963, nobody expected this BBC sci-fi series to still be going strong more than six decades later. However, an ingenious decision made after the First Doctor’s actor, William Hartnell, exited the show in 1966 meant thatDoctor Whocould continually move with the times as new actors could come in and take their place. It was at this point thatDoctor Whointroduced the concept of regeneration, meaning that Time Lords could renew every cell in their bodies and be reincarnated as a brand new person.
The clever concept of regeneration meant that the Doctor was famously played by stars like Tom Baker throughout much of the 1970s, David Tennant in the 21st century, and currently by Ncuti Gatwa asDoctor Whoonce again has revamped itself as it’s released on Disney+ outside of the UK. With 15 main incarnations of the Doctor that have transcended gender and race, this alien nation of this sci-fi protagonist truly means that anything is possible. By moving with the times and embracing change,Doctor Whohas maintained its relevance since the 1960s.
Doctor Who
Doctor Who: Doctor Who is a British sci-fi television series debuting in 1963, following The Doctor, a time-traveling alien Time Lord. The Doctor explores the universe in the TARDIS, accompanied by companions, confronting various adversaries and striving to save civilizations while addressing injustices.
