These actors look so much like other actors, it's hard to keep them all straight. But don't worry, we're here to help. Here's how to keep track of your faves and their famous doppelgangers.

Keira Knightley looks so similar to Natalie Portman that her first major film role was playing a decoy for Portman's Star Wars character, Princess Amidala.

Michelle Monaghan might be involved in her own love triangle in Hulu's The Path, but she's not the same star having an affair on Showtime's The Affair. British actress Ruth Wilson is.

Both of these celebs are equally sexy, but they're two different people. Jeffrey Dean Morgan won the heart of audiences as Denny Duquette on Grey's Anatomy. You may recognize Spanish stud Javier Bardem from Skyfall or Eat Pray Love.

Minka Kelly starred as head cheerleader Lyla Garrity on Friday Night Lights. However her doppelganger, Leighton Meester, was a Gossip Girl who never cheered a day in her life.

Chastain stars in Interstellar and The Martian. As for Howard, you probably know her from Jurassic World.

If you think Parker Posey directed and starred in Pitch Perfect 2, you may have your wires crossed. Posey is the funny lady from Louie and Josie and the Pussycats. Banks is the Pitch Perfect star.

Both are sitcom legends, but Jon Cryer's known for Two and a Half Men, while Sean Hayes rose to fame thanks to Will & Grace.

McMahon never lived in Dawson Creek's Capeside, but he did star on another long running WB show ... Charmed. Kerr takes credit as the Creek cutie.

No one twins harder to wide-eyed New Girl star Deschanel more than superstar songstress Katy Perry.

Famous Brit Tom Hardy never starred in The O.C. That's Logan Marshall Green's territory. Hardy has major roles in The Dark Knight Rises, Mad Max: Fury Road and The Revenant.

Both are comedy stars ... Hyland stars on Modern Family, whereas Kunis cut her teeth on That '70s Show.

Arrested Development alum Will Arnett is not a musical theater star who sometimes hangs out in Fargo. That's Patrick Wilson.

Margot Robbie has made a big splash in Hollywood with giant roles in Suicide Squad and The Wolf of Wall Street. She also looks an awful lot like My Name Is Earl star Jaime Pressly.

Ian Somerhalder smolders on the CW in Vampire Diaries, while fellow CW star Chace Crawford smolders on Gossip Girl. Talk about one sexy network.

Game of Thrones star Nikolaj Coster-Waldau and Lost's Josh Holloway are both ruggedly handsome and nearly identical.

Dancing with the Stars' Erin Andrews looks pretty darn similar to another beautiful blonde ... 2 Broke Girls' Beth Behrs.

Comedians Stephen Colbert and Bob Saget both wear glasses, but that's not where the similarities end.

Did you just do a double take? These immensely talented stars, Ellen DeGeneres and Edie Falco, are nearly identical.

Beautiful brunettes and practically twins, The Vampire Diaries' Nina Dobrev and Victorious star Victoria Justice are true doppelgängers.

Amy Adams was not in Wedding Crashers ... that credit goes to Isla Fisher. You probably know Adams for her work in American Hustle, Enchanted and The Fighter.

Megan Fox and Angelina Jolie were not separated at birth. We promise. They just happen to look nearly the same.

Both ladies are known for their acting abilities and singing skills, but they are not the same person. Selena Gomez rose to fame thanks to her music (and on programs like Wizards of Waverly Place), whereas Hale is known for her work on Pretty Little Liars.

Mad About You's Helen Hunt and Eyes Wide Shut star Leelee Sobieski look just like one another.

These two talents are not twins, but they sure look like they could be.

Double the handsome, double the fun ... can you tell the difference between each one?

Guardians of the Galaxy star Zoe Saldana did not appear in the film Crash. That was Thandie Newton.