'Cause and Effect' and 12 more Star Trek time travel episodes
There are more than a few Star Trek episodes that deal with time travel. Quite a few, in fact, especially when one takes into account that the Temporal Prime Directive instructs Starfleet officers not to interfere or do anything that could change history. But, thankfully for Captains like Kirk and Picard, some officers take such directives more as "strong suggestions."
Source: syfy.com