There are loads I can think of. Of course, I am a Doctor Who fan, and that series was all about time travel! It might be simpler to list the episodes that didn't involve time travel....<br /><br />There are some that come to mind as doing interesting things with time travel, though:<br /><br />THIRD DOCTOR<br />"Invasion of the Dinosaurs"<br />The FX are amazingly corny in this one, but if you can look past that, it's an interesting story. The Doctor and Sarah Jane Smith return to London and find it deserted -- well, almost deserted. Martial law has been imposed; only the Royal Army, a UNIT taskforce, and looters remain in the city. The reason is that dinosaurs have been popping up all over the city, terrorizing the locals and then mysteriously vanishing. Nobody sees them appear, and nobody sees them disappear either -- except the Doctor, who as a Time Lord is aware of time going backwards when they disappear. Someone is pulling the beasts forward from the Mesozoic Era as part of a plan to create a utopia on Earth.<br /><br />FOURTH DOCTOR<br />"City of Death"<br />One of the all-time most popular episodes, this was the first to be filmed outside of Great Britain; a few outdoor scenes were shot on location with a small crew in Paris. The Doctor and Romana stumble into an investigation into high-stakes art theft (including a plot to steal the Mona Lisa) which turns out to be financing dangerous and unstable experiments in time travel. But the villain behind it, Count Scarlioni, clearly already has some ability to travel in time -- he's got six genuine Mona Lisas that have been bricked up in his cellar for four hundred years, painted by Leonardo da Vinci himself, and that's one heck of a coincidence. So why does he need to finance time travel experiments if he was able to get Leonardo to paint him some copies and leave them for himself to find in 1979? Watch for a hilarious cameo appearance by John Cleese.<br /><br />FIFTH DOCTOR<br />"Mawdryn Undead"<br />The TARDIS is <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>