From 'Back to the Future' to 'Looper': 19 great time travel movies

If "Back to the Future" was a shiny, happy version of time travel from the '80s, the "Terminator" series is its dark-side doppelganger. The killer cyborg traveled back in time to kill a future savior of humanity before he's even born. Then he gets reprogrammed and sent back to protect the guy he was supposed to kill. All the while he's battling increasingly sophisticated cyborgs ... which makes you wonder why the Terminator didn't get the same liquid-metal upgrades.