Star Trek: 15 Greatest Ever Time Travel Episodes
9. Cause And Effect - TNG
Let's be honest here, Cause & Effect has a lot of scientific contrivance (specifically in the idea that previous iterations of a time loop could be heard by the next loop and Data being able to communicate with himself), but the way it inventively used time travel was brilliant.
It opens with a quite stunning - and quite literal - bang, with The Enterprise blowing up and killing everyone. From there, it gets more tense. The ship is trapped in a time loop, unaware of what is happening until Doctor Crusher hears voices from the alternate timeline from just before she and her fellow crew are all killed. Chilling.
It's an utterly captivating conceit, having the same devastating few hours replayed with the crew desperately trying to find out a clue to avoiding their fate. Sort of like Quantum Leap, only with more stakes. And the final pay-off that finally sees them meet the Captain of the older Federation Sip - Kelsey Grammer no less - is one of the single greatest cameos in the show's history.