Star Trek: 15 Greatest Ever Time Travel Episodes

Tapestry is one of those brilliant The Next Generation episodes when Q decides to intervene in Picard's life just to apparently f*ck with him because he's having a slow day in the Continuum. It's also brilliant because it riffs extremely heavily on It's A Wonderful Life, taking Picard into an alternate timeline in which he wasn't stabbed through the heart in a bar fight.

The premise is genius: in the present, Picard's fake heart malfunctions and Q appears (as God, obviously) to send him back for a second chance at life to stop the heart injury that required the replacement. Unfortunately, it quickly transpires that the artificial device and the stabbing were crucial to Picard becoming who he is, and he eventually realises that he would rather die a strong man than live as a wuss.

Obviously neither is necessary, as his bionic heart is fixed (again, having cake and eating it springs to mind), but Tapestry is a delightfully humanist episode with a very worthy message about mistakes defining lives in a positive way, and it is absolutely hilarious at times thanks to Q. Plus, Riker and Troi get to act as complete dicks in the restored future to the weakling Picard, which is clearly a lot of fun.