1 of 16
Lisa Robin Kelly for Christina Moore (Laurie Forman on 'That '70s Show')
Lisa Robin Kelly was introduced as Laurie Forman in That '70s Show's first season. Making her debut in the second episode, "Eric's Birthday," Kelly played the older sister to Topher Grace's Eric Forman. The actress continued to play Laurie on and off for five years, making her last appearance in season 5's "Celebration Day." In the first episode of the sixth season, Laurie was played by Christina Moore with little explanation given for the change. Moore portrayed the promiscuous older sister for six episodes, wrapping her run at the end of the show's sixth season in 2004.
2 of 16
Alessandra Torresani for Mae Whitman (Ann Veal on Arrested Development)
Mae Whitman may be famous for her early role on Arrested Development, but she was not the first actress to play Ann Veal on the Emmy-winning sitcom. The character of George Michael's girlfriend was introduced by Alessandra Torresani in the season 1 episode "Let 'Em Eat Cake" in 2004. Whitman first played Ann a few months later, appearing in the season 2 episode "The One Where They Build a House."
3 of 16
Janet Hubert for Daphne Reid (Vivian Banks on The Fresh Prince of Bel-Air)
Fresh Prince of Bel-Air viewers first met Aunt Viv in 1990 in thanks to Janet Hubert. Hubert played Vivian Banks from the show's September 1990 premiere episode through 1993, taking her last bow in the season 3 episode "Six Degrees of Graduation." Amid rumors of a feud with Fresh Prince star Will Smith, Hubert was replaced for the sitcom's fourth season. Daphne Reid stepped into Aunt Viv's shoes in the season 4 premiere, continuing the character's story from 1993 until the show's wrap in May 1996.
4 of 16
Dick York for Dick Sargent (Darrin Stephens on Bewitched)
Samantha (Elizabeth Montgomery) met her match in Darrin Stephens on Bewitched, but the adman wasn't even played by the same actor through the show's eight-year run. Dick York originated the role, playing Darrin from the 1964 series premiere "I, Darrin, Take This Witch, Samantha" through season 5's "Samantha and Darrin in Mexico City," five years and 17 episodes later. Dick Sargent then took over, first playing Darrin in the season 6 premiere, "Sam and the Beanstalk," and continuing to do so until the show came to a close in 1972.
5 of 16
Lily Nicksay for Lindsay Ridgeway (Morgan Matthews on Boy Meets World)
Boy Meets World premiered in 1993 with Lily Nicksay playing Morgan Matthews, the little sister to Ben Savage's Cory Matthews. She continued the role through the end of the second season, bidding adieu in the 1995 season finale "Home." Morgan was nowhere to be seen the first half of the third season, finally returning in 1996's "A Kiss Is More Than a Kiss" with Lindsay Ridgeway playing the character. The show nodded to the absence, as Cory told his sister, "Morgan, long time, no see!" and she responded, "Yeah, that was the longest timeout I've ever had."
6 of 16
Barbara Bel Geddes for Donna Reed for Barbara Bel Geddes (Miss Ellie Ewing on Dallas)
Dallas premiered in April 1978 with Barbara Bel Geddes playing Miss Ellie Ewing. She continued the role for six years, leaving after the season 7 episode "End Game" in May 1984. In November 1984, Donna Reed stepped into her shoes, taking a turn as Miss Ellie Ewing beginning with the season 8 episode "Homecoming." Another swap was in the works, however, as Reed exited the show a year later, as Geddes made her return. Reed's final appearance was in May 1985's "Swan Song," followed soon after by Geddes' return in September 1985.
7 of 16
Dixie Carter for Mary Ann Mobley (Maggie McKinney on Diff'rent Strokes)
Dixie Carter introduced the character of Maggie McKinney in Diff'rent Strokes' sixth season. She played the aerobics instructor for one year, leaving the show in 1985's season 7 episode " Blue Collar Drummond." Mary Ann Mobley took over in the eighth season premiere, playing Maggie in the final run of episodes.
8 of 16
Al Corley for Jack Coleman (Steven Carrington on Dynasty)
When Dynasty made its debut in January 1981, Al Corley was playing the character Steven Carrington. Corley portrayed the oil heir for about a year, exiting Dynasty after the 1982 season 2 episode "The Cliff." Jack Coleman took over from there, making his debut as Steven in the 1982 season 3 episode "Acapulco." Coleman stayed on the show for six years, picking up a final appearance in 1988's season 8 episode "Colorado Roulette."
9 of 16
Jake T. Austin for Noah Centineo (Jesus Adams Foster on The Fosters)
Jake T. Austin picked up a big gig in 2013 when he originated the role of Jesus Adams Foster on The Fosters. He played the young man for two years, wrapping his run after the season 2 episode "The End of the Beginning" in March 2015. The character was then absent for a handful of episodes, finally returning in August 2015 with Noah Centineo appearing as Jesus in season 3's "Lucky."
10 of 16
Ed Skrein for Michiel Huisman (Daario Naharis on Game of Thrones)
When Game of Thrones fans first met Daario Naharis in the show's third season, the sellsword was played by Ed Skrein. When the fourth season debuted in 2014, however, Michiel Huisman stepped into the role of Daario.
11 of 16
Mike Evans for Damon Evans for Mike Evans (Lionel Jefferson on The Jeffersons)
Mike Evans joined The Jeffersons as Lionel Jefferson, playing the young man in the series premiere. He continued his turn through the first season, but the role went to Damon Evans in The Jeffersons' second season. The actor portrayed Lionel for three years, exiting the show after 1978's season 4 episode "Lionel Gets the Business." In 1979, Mike returned, taking on Lionel in the season 6 premiere and continuing the gig through the 1985 episode "Sayonara: Part 2" in the final season.
12 of 16
Clayton Moore for John Hart for Clayton Moore (The Lone Ranger on The Lone Ranger)
In September 1949, The Lone Ranger made its debut, with Clayton Moore playing the title character in "Enter the Lone Ranger." Moore continued to play the Lone Ranger through March 1951, leaving after the season 2 episode "Backtrail." When the third season premiered in September 1952, John Hart was the man behind the mask. Hart played the Lone Ranger until September 1952, exiting after the season 3 episode "The Red Mark." Moore then made his return, coming back to the role in the September 1954 season 4 premiere "The Fugitive" and continuing the role until the show's wrap in June 1957.
13 of 16
Jeremy Gelbwaks for Brian Forster (Christopher 'Chris' Partridge on The Partridge Family)
When fans first took in The Partridge Family, Jeremy Gelbwaks was playing the role of Chris Partridge. The young man appeared on the show for about a year, playing the drummer through the season 1 finale "A Knight in Shining Armor" in 1971. When season 2 debuted, Brian Forster was in the role. Forster continued to play Chris for three years, going out with the show's final episode in 1974.
14 of 16
Ryan Bittle for Jeremy Garrett (Todd Wilkins on Sweet Valley High)
Sweet Valley High made its TV debut in September 1994, recruiting Ryan Bittle for the role of high school dreamboat Todd Wilkins. Bittle held the gig for two years, eventually leaving after the season 2 episode "A Look Back in Anecdotes" in 1996. He was then replaced by Jeremy Garrett, who took on the role of Todd the same year. Garrett continued his turn through the show's final run of episodes in 1997.
15 of 16
Beverley Owen for Pat Priest (Marilyn Munster on The Munsters)
Viewers met the Munsters in September 1964, getting an introduction to Marilyn Munster thanks to actress Beverley Owen. Owen played the normal family member through the 13th episode in December 1964, passing the part to Pat Priest, who made her first appearance as Marilyn the following week in "Grandpa Leaves Home." Priest continued to portray Marilyn through the rest of the show's run.
16 of 16
Lecy Goranson for Sarah Chalke for Lecy Goranson for Sarah Chalke (Becky Conner on Roseanne)
Lecy Goranson and Sarah Chalke did quite the complicated dance throughout the eight-year run of Roseanne. The sitcom debuted in October 1988 with Goranson playing Becky Conner. She continued to do so for five years, leaving the gig after the season 5 episode "Daughters and Other Strangers" in May 1993. Chalke then stepped in, picking up the role of Becky in November 1993's season 6 episode "Homecoming." Chalke then exited in 1995, when the part went back to Goranson, who played Becky on and off from September 1995 through May 1996. Clarke popped back up during this time, taking on Becky for the final run through the series finale in May 1997.