It's not uncommon for movie time travelers to run into themselves. Sometimes the same actor will play the same character at different ages – in the same scene together! 'Terminator Genisys' is just the latest example. Here are some others.

Back to the Future Part II (1989)

There are so many versions of Michael J. Fox in this movie that it's hard to keep track. But our favorite bit has 2015 Biff (Thomas F. Wilson) meeting 1955 Biff (Thomas F. Wilson)... and both calling each other a butthead.

X-Men: Days of Future Past (2014)

It requires a little help from Wolverine (Hugh Jackman) and Kitty Pride (Ellen Page), but James McAvoy and Patrick Stewart, playing Professor Charles Xavier at two different ages, get to see each other on the psychic plane.

Looper (2012)

What happens when a hit man gets sent back in time to be killed by his past self – and then he escapes? Bruce Willis and Joseph Gordon-Levitt, both playing said hit man, try to answer this question in the cult sci-fi hit.

12 Monkeys (1995)

Madeleine Stowe says, “Spoiler alert!” Though even if you figure out early on that a time traveler's (Bruce Willis again) childhood memory is of seeing his own adult self, '12 Monkeys' still has a few more surprises up its sleeve.

The Kid (2000)

Incredible as it may be, this is the third movie in which Bruce Willis has an encounter with his younger self (Spencer Breslin). Here's the good news: this heartwarming fantasy is far less disturbing than either '12 Monkeys' or 'Looper.'

Lost in Space (1998)

We still prefer Jonathan Harris' campy Dr. Smith from the 1960s TV show. But this big-screen adaptation does have the Robinson family dealing with both Dr. Smith (Gary Oldman) and future mutant-spider Dr. Smith, so there's that.

Zathura (2005)

When three kids (including Josh Hutcherson and Kristen Stewart) find themselves lost in space as well, an astronaut (Dax Shepard) comes to their aid, and... well, let's just say he has a lot in common with one of them.

Timecop (1994)

Police officer Jean-Claude Van Damme hops back and forth between 1994 and 2004, but it's an evil senator (the late Ron Silver) who shows why, at least according to this movie's rules, it's not a good idea to bump into your younger self.

Star Trek (2009)

Zachary Quinto is such a dead ringer for Leonard Nimoy that, with a little makeup, he could have passed as both Spock and Spock Prime. But why bother when Nimoy himself was available to film this celebrated scene?

2001: A Space Odyssey (1968)

The climax of Stanley Kubrick's mind-bending classic has astronaut Keir Dullea seeing himself at four different ages – even as an elderly man and a fetus. We'd call a spoiler alert on this if we could understand what it all means.

Predestination (2014)

Here's a genuine spoiler warning for the twist-filled Ethan Hawke/Sarah Snook drama, in which a number of time travelers screw up each other's lives. How many time travelers, exactly? That’s up to ‘Predestination’ to reveal.