A time loop, in the context of this list, is when you go back in time and interfere with your own history, often running into yourself in the process. Some time travel movies are obsessively worried about paradoxes and unraveling the universe and such, but what fun is time travel if you must think about such weighty things? And if, indeed, the time line must be preserved, at least let us learn that it was for the best, and only through the efforts of our future self coming back to right some wrong.
I'm sure this list is skewed by my age; are there any good time loop movies that predate 1989?
10. A Sound of Thunder (2005)
This movie succeeds in being as much a mess as they say our timeline will be if we starting traveling through time. In an interesting twist, characters don't come back to the present to find it changed. Rather, their tiny changes in the past only slowly assert themselves in the present, as if it takes Time a bit of time to catch up. If you haven't already endured this heap, don't bother. If you have, I'll see you at therapy next week.
9. Timeline (2003)
This is a great time travel movie because of convincing character behavior (our team is scared to death being stranded in the past), but is also fun as events come full circle, with the characters realizing that they are the very legends they have been studying in an ancient ruin.
8. Grand Tour: Disaster in Time (1992)
Jeff Daniels runs an inn, let by some folks who have come from the future to watch Daniels's town be destroyed by a meteor. Daniels catches wind of their plot, and travels back in time to save the town before the meteor hits. And, since my Aunt Anna is one of the townspeople, this is a very good thing.
7. Timecop (1994)
What happens if you try to occupy the same space as your past self? Well, it's gruesome. What happens if you return to your present, only to find that your friends don't really know you anymore? Mention their wife's cooking. This has one of the better loops that make us reconsider how a character was behaving, since we later learn that Mia Sara had just been visited by her future husband, right before her present husband meets up with her.
6. The Butterfly Effect (2004)
Ashton Kutcher has been blacking out his entire life, and now he finds that he can go back in time to control his body during those blackouts. Each time he does this, though, he changes things, and typically for the worse. This movie is super dark. It's not really about how you shouldn't mess with time travel. It's more about how it takes a lot of work and suffering to fix a messed up situation.
5. Deja Vu (2006)
It's frustrating in these movies when Hero1 is inexplicably thwarted, and later, when Hero2, having encountered their previous self, has the chance to change history, but doesn't, because of paradoxes and what not. (I've never even seen a paradox, so I'll be darned if I'd let one stop me!) It's much more satisfying when, in that same scenario, Hero2 thwarts Hero1 (thus preserving the timeline), but for a different reason, meaning that Hero1's actions would have been destructive, and the guardian angel that stopped them from making what would later be revealed as a mistake is actually their future self. You get all that? When Denzel Washington says to send him back, you had best do as the man says.
4. Back to the Future, Part III (1990)
The movie seems to believe in paradox when it's convenient. It's okay that Marty McFly turned his dad into a super cool guy, but when McFly travels back to the '50s for a second time, he is extra careful not to interfere with his previous interfering self. In an unusual feat for a movie, McFly's duplicative presence doesn't undermine the victory of his former self. Though it is great to see the look on Doc's face when, having sent McFly back to the future, he turns around and sees another McFly running toward him.
3. Bill & Ted's Excellent Adventure (1989)
This movie answers the age old question of whether Abe Lincoln and Genghis Kahn could have been pals. It also shows that our heroes so understand time travel that they need merely think of something ("remember the trash can") for it to happen, because they are deciding that after all the commotion has died down, they will travel back in time, and set up the prank they so hastily planned while in the thick of things.
2. Millenium (1989)
This low budget '80s movie is one of the better time travel movies, but also has some mind-bending twists, where we are trying to keep distinct the timelines of our two protagonists. When Kris Kristofferson meets Cheryl Ladd for the first time, she already knows him. When he meets her for the second time, she's never met him before. When he meets her for the third time, it's only the second time she's meeting him. Etc. That stuff blows my mind.
1. Primer (2004)
Two guys create a time machine with two very creative restrictions. 1) You cannot travel back in time beyond when the time machine was invented. 2) You must sit in the time machine for as long as you want to go back in time. E.g. if you want to go back in time one day, you must sit in the time machine for a day. You can't use the machine to go forward in time; instead, you must wait for your other self, who occupies the same time you've just come back to, to finally get in the machine to go back in time, and then poof! suddenly you are the only you in the timeline. Aside from being awesome in every way, this film is incomprehensibly convoluted. There are so many different versions of the protagonists running around, and so many copies of the time machine, I find it impossible to keep straight. But the filmmakers have been careful with their creation, and it will reward study. Here is one person's attempt to unravel to loops. Here is another person's more successful attempt.