They kept it all in the (fictional) family.
1. Bill Hader and Anna Kendrick played siblings (also Santa's children) in the Christmas movie Noelle and have been "'quietly' dating for over a year."
A source told People Magazine, "They met years ago. She's hosted Saturday Night Live and they've done a movie together, but they got together well after the movie. They are both very private people, and with the pandemic, it was easy to keep it quiet," they continue. "They're both hysterical so they must keep each other laughing all of the time. She's really, really happy."
2. Georgia Moffett played David Tennant's daughter on Doctor Who. They were rumored to have started dating around 2008 then got married in 2012, and have been together ever since.
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Georgia (whose father actually played the fifth Doctor from 1981–1984) guest-starred on the show, which was how she and David first met. They got together soon after and got married in 2012. They have five kids together.
3. Susan Dey and David Cassidy played siblings on The Partridge Family, and while Susan had a huge crush on David, he didn't initially feel the same. David shared that he finally gave in but "couldn't think of her as anything but [his] sister."
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In his memoir, C'mon Get Happy: Fear and Loathing on the Partridge Family Bus, David shared that Susan "lacked the slutty aspect of a female" that he found attractive. He also revealed that Susan was so determined to get with David that he finally gave in, and he ended up regretting it later. He said, "She was sweetness and innocence, a good girl, and I couldn't think of her as anything but my sister."
4. Maureen McCormick and Barry Williams played siblings Marcia and Greg Brady on The Brady Bunch and dated for a bit in real life — Barry was actually Maureen's first kiss!
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In 2013, Barry did an interview with Oprah Winfrey and finally revealed that he and Maureen, his onscreen sister, actually dated in real life. Greg even shared, “In fact, I was her first kiss. And that was in Hawaii while we were filming those episodes. We snuck away, it was a full moon and walked along the sand. Well, I knew where that was headed. Of course, I set it up.”
5. John Travolta played Diana Hyland's son in The Boy in the Plastic Bubble and then began dating in 1976 until Diana's death in 1977.
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6. Matthew Broderick and Jennifer Grey played siblings Ferris and Jeannie Bueller in Ferris Bueller's Day Off and started secretly dating while they made the film.
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Jennifer even said, "It started while we made the film. It was tricky because it was a secret. No one knew.” While the two were vacationing together in Ireland, they got into a tragic car accident that killed two people and left both Matthew and Jennifer with severe injuries and chronic pain. The couple broke up shortly after.
7. Eleanor Tomlinson and Harry Richardson played sister in brother in Poldark and then dated for about a year until their breakup in 2011.
Eleanor and Harry met on the set of Poldark and began dating shortly after Harry joined the cast in Season 3. They were first spotted together during the summer of 2017, the same time their show's third season was airing.
8. Emily VanCamp and Chris Pratt played brother and sister duo Bright and Emily Abbott on Everwood, then dated for three years.
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Chris even told TV Guide, "Yeah, we've pretty much gotten used to the response of, 'Ew, that's weird. That's creepy...The people who know us are happy and probably expected it to happen eventually. But yeah, every once in a while we get that one person that's like, 'That's really creepy. You just kissed your sister.'"
9. Ian Somerhalder and Maggie Grace played step-siblings Boone Carlyle and Maggie Rutherford on Lost, then began dating after their characters were killed off the show.
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They broke up in 2007, but in 2016, Maggie told New You that she and Ian "are still very good friends."
10. David and Tamela Mann have been married since 1988 but starred as father and daughter in the movie and TV versions of Meet the Browns and have reprised their role in several Tyler Perry Cinamatic Universe projects.
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David and Tamela have worked professionally together on several projects, including their BET reality show It's A Mann's World. They have raised five children together and have 13 grandchildren.
11. Michael C. Hall and Jennifer Carpenter played brother and sister on Dexter, eloped in 2008, got divorced in 2010, and then continued to play the roles until the end of the series in 2013 and returned for the 2021 revival.
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They first met on the set of Dexter and began secretly dating shortly after. They eloped on New Year's Eve in 2008 and were married for two years before getting divorced in 2010. The two continued to work together until the show's series finale in 2013 and both returned to play their respective roles in Dexter: New Blood.
12. Shannen Doherty and Jason Priestley played brother and sister on Beverly Hills, 90210, and years after the series ended, Jason admitted to briefly dating Shannen along with some of his other co-stars.
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14. Michael Emerson and Carrie Preston have been married since 1998 and Carrie ended up getting to play Michael's mother on Lost all because of a joke.
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Carrie told Entertainment Weekly, "It was supposed to be just a couple of episodes — but then he turned into the main villain. So I thought of Hawaii as the place that stole my husband. Of course, nobody can stay mad at Hawaii, so I thought, 'I've got to figure out how I can spend more time out there.' I used to joke, 'Wouldn't it be hilarious if I played your mom in a flashback?' Michael shared that joke [with] the producers, and the next week, there was a phone call to my agents: 'Can Carrie play Michael's mother in a flashback [on a season 3 episode]?' We were howling. We thought, 'This is insane and a little freaky, but the fans are gonna love it.' Sure enough, I've gotten many Oedipal jokes, jokes [like], 'I've always mothered him, but now I get to really do it on television.' I got to go out in the jungle and simulate giving birth to my husband. Not many people get to say that."
15. Lauren Graham and Peter Krause played siblings Sarah and Adam Braverman on Parenthood, and after years of trying to keep Peter in the friend zone, Lauren finally started dating quietly dating him during the run of their show.
The two first met way back in 1995 on the set of Caroline in the City, but they didn't start dating until starring on Parenthood together. Lauren told Good Housekeeping that she had a rule about not dating any actor types and tried to keep her relationship with Peter in the friend zone. She later admitted that their friendship evolved into a relationship. She said, "It was like, 'You like me, and I like you.' It gave me an understanding of life: This is how things happen, and it's completely random."
16. Tom Hanks and Rita Wilson played siblings in Sleepless in Seattle just five years after getting married in 1988.
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They first met on the set of Bosom Buddies in the early '80s, but reunited years later on the set of Volunteers and began dating shortly after. They've worked on several other projects together, including The Bonfire of the Vanities, That Thing You Do!, and Larry Crowne. They eventually got married in 1988, and together they have two kids, plus Tom's two kids from his previous marriage.
17. Evan Rachel Wood and Shane West played siblings on Once and Again when Rachel was 12 and Shane was 21, nine years later, they reunited and started dating.
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When the two reunited, they were seen holding hands at a club. When asked if they were together, Evan said, “I think you can put two and two together. I won’t confirm or deny it, but I don’t think I have to.”
18. Kirstie Alley and Parker Stevenson married in 1983 and then went on to play siblings on the miniseries North and South: Book II.
The two first met in 1981 when they ran into each other at a restaurant in LA. They began dating shortly after, got married in 1983, and had two kids: Lillie and William. They got divorced in 1997.
19. Amy Poehler and Will Arnett were actually married in 2003, before they went on to play the sibling-skating-duo Stranz and Fairchild Van Waldenberg in Blades of Glory.
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Will and Amy actually first met back in 1996 after he saw Amy perform, and they officially began dating four years later. They've appeared in several other projects together, including Arrested Development, Parks and Recreation, and Horton Hears a Who! and divorced in 2014.
20. Milo Ventimiglia starred as Hayden Panettiere's uncle on Heroes, they began dating during the show's run in 2007 and stayed together for about two years.
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Milo was 29 and Hayden was 18 when they started dating, and a source told People Magazine, "Hayden’s mom adores Milo. She thinks he’s so cute. She tells her friends that he’s her boyfriend. She’s very proud.”
21. Drew Barrymore and David Arquette played siblings in Never Been Kissed and years later David confirmed that the two had dated years before (even though Drew denied it).
Drew and David had actually known each other for a while before they appeared in Never Been Kissed. While Drew denied any romance between the two, David told PeopleTV, “We also dated, but she denied it on Howard Stern. But, we dated, Drew!" He later clarified that their relationship happened before they worked on the movie together.
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