There are obviously spoilers ahead for several TV shows.
1.First, when Robin Hood first appeared in Once Upon a Time Season 2, he was played by Tom Ellis in a guest-starring role. However, when Robin's role got much bigger in Season 3, he was recast with Sean Maguire, who played him for the remainder of the series.
2.In the pilot of The Golden Girls, Charles Levin starred as Coco, the ladies' housekeeper. However, he disappeared after the first episode. Originally, Estelle Getty was only going to be a guest star as Sophia, but after she was a hit with audiences, the show promoted her to a main character and ultimately cut Coco.
3.For the first two seasons of Bridgerton, Francesca Bridgerton was played by Ruby Stokes. However, when the series returns for Season 3, she's now played by Hannah Dodd, and reportedly has a bigger role.
4.In the backdoor pilot for Private Practice, a spinoff of Grey's Anatomy, Naomi Bennett was played by Merrin Dungey. However, when the show was picked up, Audra McDonald assumed the role in Season 1.
5.Keahu Kahuanui played Danny on Teen Wolf for the first three seasons. However, after Season 3, Danny left and never popped back up again, even after he revealed he knew about the existence of werewolves the entire time.
6.Xochitl Gomez portrayed Dawn Schafer in The Baby-Sitters Club Season 1. Then, Kyndra Sanchez assumed the role for the show's second and final season. Xochitl stepped away from the role in order to star in Doctor Strange in the Multiverse of Madness.
7.Jake T. Austin notably starred as Jesus Adams Foster in the first two seasons of The Fosters. However, he left the show after Season 2 and was replaced by Noah Centineo. The show played off Jesus' appearance change as he simply grew up while he was away at a boarding school.
8.Ross Butler portrayed Reggie in Riverdale Season 1 before being replaced by Charles Melton for the rest of the series. Ross explained he decided to leave Riverdale in order to focus on having a bigger role on 13 Reasons Why.
9.Family Matters originally centered heavily on the Winslow family, however, after audiences loved Steve Urkel so much, the central storylines on the show shifted. This led to the youngest Winslow daughter, Judy, disappearing one day as if she never existed. People often joke that Judy went upstairs one day, and never returned.
10.Janet Hubert left The Fresh Prince of Bel-Air after she was offered a "bad deal" during Season 3. The series famously recast Aunt Viv, who was then played by Daphne Maxwell Reid for the rest of the show's run.
11.In The West Wing Season 1, Moira Kelly starred as Mandy Hampton, a White House media consultant who was a main character. However, when Season 2 began, Mandy was gone. The disappearance of her character even led to fans coining the term "Mandyville," which was used when any other character just vanished during the show's run.
12.In Roseanne Season 6, Jackie gives birth to her son Andy. After appearing in the rest of the OG series, he was never mentioned or seen in the spinoff The Conners. Ultimately, the show decided just to have Andy disappear and the series acts as though Jackie never had a child.
13.Friday Night Lights introduced Santiago, who moves in with Buddy Garrity and joins the Dillon Panthers after Lyla meets him at a juvenile detention center. He became an important member of the team but was never seen again after Season 2. In an interview in 2016, Ben Ciaramello explained that his character's storyline was likely cut short due to the 2007–2008 Writers Guild of America strike.
14.In Game of Thrones Season 3, Ed Skrein played Daario Naharis; however, after the season, he was replaced by Michiel Huisman, and Daario went on to have a bigger role, too. At the time, Ed said, "My plan was to stay with Game of Thrones for the long haul. That was always my plan. I would have loved to. It was a wonderful experience, but politics led to us parting ways."
15.And finally, in the pilot of Brooklyn Nine-Nine, Scully and Hitchco*ck are seen with Daniels, another NYPD detective who hangs out with Scully and Hitchco*ck. After the first episode, she's never seen again.
