1. Sarah Hyland and Mila Kunis
The "Modern Family" and "Ted" actresses say they get mistaken for the other all the time. Upon meeting each other in December 2010 at a Nylon party, the two decided they'd pretend to be each other in public.
"She came up to me and said she gets called me all the time too," Hyland told InStyle. "She said that sometimes she pretends she's me because it makes her feel young. I asked if I could pretend to be her next time somebody asks me if I'm her, and she said OK."
2. Natalie Portman and Keira Knightley
Short, long, curly, or straight hair, Keira Knightley and Natalie Portman look strikingly similar no matter how you pair them.
The two look so similar, Knightley played Portman's double, Sabé, in "Star Wars: Episode I - The Phantom Menace."
3. Ralph Fiennes and Liam Neeson
Neeson has said people often confuse the "Harry Potter" and "Taken" stars. That shouldn't be too much of a surprise since the two have starred in multiple films alongside each other ("Schindler's List," "Wrath of the Titans"). The only difference is that Fiennes usually plays the bad guy while Neeson's the hero.
"He is one of my best, best, dearest friends. I keep getting fans and stuff mixing me up with Ralph because we have very similar profiles," Neeson said on The Jonathan Ross Show in 2014. "So I've been complimented on winning a Tony Award for my Hamlet, he's been complimented on the 'Taken' movies."
4. Amy Adams and Isla Fisher
Despite the eye color difference, the "Arrival" and "Bachelorette" actresses get confused often. Fisher joked about the duo's striking resemblance in her cover story with Allure in January 2009.
"If 'Shopaholic' is a hit, then it was Isla Fisher in the movie," said Fisher. " ... and if it doesn't work out, it was Amy Adams."
Fisher used Adams' photo in her Christmas card this past year and fooled both family and friends.
next slide will load in 15 secondsSkip AdSkip Ad5. Katy Perry and Zooey Deschanel
The "New Girl" actress was initially kind of frustrated when fans confused the two.
"It's a little bit annoying, to be totally blunt," Deschanel told MTV back in 2009. "The only similarity that we have is that we look a little bit alike."
The actress has since appeared to warm up to the similarity.
"I was relieved because everyone kept saying ‘this girl looks so much like you,'" she told Letterman in November 2012. "And then I met her and I was like, 'Thank God she’s attractive!' I was worried she was gonna be an unattractive person."
6. Gerard Butler and Clive Owen
We're not the first to confuse the "300" and "Children of Men" actors.
When it comes down to it, we remember Butler is more likely to star in romantic comedies ("Bounty Hunter," "P.S. I Love You").
7. Susan Sarandon and Sigourney Weaver
Susan Sarandon said at the Glamour Women of the Year Awards in 2016 that she and Weaver get mistaken for one another.
"I wanna just clarify a few things. Sigourney may have left the stage but we are two different people. I have taken credit for 'Alien' many times and she's signed autographs for me,” she said at the ceremony, according to Page Six.
In 2014, Sarandon wrote an op-ed suggesting Weaver is her "bad-ass alter ego."
8. Heath Ledger and Joseph Gordon-Levitt
9. Chelsea Handler and Elizabeth Banks
Elizabeth Banks admitted she pretends to be Handler when people confuse her with the comedienne.
"I was sitting in Toronto and a guy walked up to me and said, 'Oh my god, my girlfriend loves you. She would die if I didn't get your autograph. This is so exciting!'," she said during an appearance on Lately's former show "Chelsea Lately" in 2011. "He's like, 'I just love your books. I mean, My Horizontal Life...' I was like, 'Oh, he thinks he's meeting Chelsea Handler.' I couldn't ruin it for him!"
next slide will load in 15 secondsSkip AdSkip Ad10. Selena Gomez and Lucy Hale
11. Jeffrey Dean Morgan and Javier Bardem.
When Jeffrey Dean Morgan entered Seattle Grace Hospital on ABC's "Grey's Anatomy" we had to do a double take to make sure he wasn't the Academy Award winner.
Morgan is now breaking hearts on "The Walking Dead."
12. Jessica Chastain and Bryce Dallas Howard
The actresses are well aware that fans get them mixed up.
"We did 'Help' together and that was the first time we like grabbed each other and said, 'Let's look in the mirror,'" Chastain told Jimmy Fallon in 2015. "And we looked at our faces side by side and we were like, 'Okay, we look alike.'"
Chastain recalled how she was mistakened for the "Jurassic World" star later and how she sometimes just goes with it. The two are good sports about it though and have tried to clear up all the confusion.
Howard made a short dubsmash clip where she let's people know who's who. It caught the attention of Chastain who shared it on Instagram. In May 2015, Chastain shared a funny image on Twitter poking fun at how people can't tell them apart.
13. Ryan Seacrest and Joel McHale
14. Penelope Cruz and Salma Hayek
next slide will load in 15 secondsSkip AdSkip Ad15. Will Ferrell and Chad Smith
The comedian and Red Hot Chili Pepper drummer know they look so similar that they took their rivalry to "Jimmy Fallon" in 2014 in a drum-off. The pair even dressed alike.
You can watch their competition here and see their equally humorous interview here.
16. Leelee Sobieski and Jennifer Lawrence
17. Jesse Eisenberg and Michael Cera
People mix these actors up all the time, according to "Arrested Development" actor Cera.
"I bumped into Jesse on the street once and he told me he gets it once a day," Cera told the New York Post in 2014. "People think he's Michael Cera."
Cera said he gets mistaken for other people too, including Jon Heder ("Napoleon Dynamite").
18. Jennifer Connelly and Demi Moore
If it weren't for Connelly's fuller brows, we would think these two were interchangeable.
19. Nina Dobrev and Victoria Justice
next slide will load in 15 secondsSkip AdSkip Ad20. Nathan Fillion and Jeremy Renner
Whenever we flip past ABC's "Castle" we think we're catching sight of "The Avengers" star on screen. In 2014, Fillion took to Twitter to discuss various celebs that fans think he looks like. How did he grade Renner? "Brothers."
Fillion said he has also spoken with Jason Bateman about their resemblance to one another.
21. Jordin Sparks and America Ferrera
A lot of people think the "Ugly Betty" star and season six winner of "American Idol" look similar, whether their hair is up or down.
22. Paul Reubens and Alan Cumming
Only one of these actors is Pee Wee Herman. The other you probably know from his role on "The Good Wife."
23. Mark Wahlberg and Matt Damon
Even Matt Damon says he suffers from a case of mistaken identity every now and then with the "Transformers" actor. In 2013, "The Martian" actor told Absolute Radio that he discussed the fan confusion with Wahlberg.
"I've talked to Mark about this because he gets people [that] come up and say, 'I love you in 'The Bourne Identity,'" he said. "So Mark and I have a deal. If we're mistaken for one another, we have to be as polite as possible."
Damon said he has even signed his name as Mark's.