X-Men: Days of Future Past (2014)

Uncanny X-Men #141–142, 1981 Two issues by Chris Claremont and John Byrne that set the template: in a future where Sentinels hunt mutants, the telepath Rachel sends Kitty Pryde's mind back into the body of her thirteen-year-old self to stop the assassination of Senator Kelly that started it all. Sending a mind rather than a body is a neat rule, because it keeps one Kitty in each time and spares the story any meeting-yourself muddle. The ending is the bit that rewards a second read. Kelly is saved, yet he restarts the Sentinel programme anyway, so the fix is partial and the future it was meant to erase never feels safely gone. At two issues, it is also the quickest read here.