http://www.filmsite.org/epicsfilms.html indicates "Epic Films often take an historical or imagined event, mythic, legendary, or heroic figure, and add an extravagant setting and lavish costumes, accompanied by grandeur and spectacle and a sweeping musical score. Epics, costume dramas, historical dramas, war film epics, medieval romps, or ‘period pictures’ are tales that often cover a large expanse of time set against a vast, panoramic backdrop … they follow the continuing adventures of the hero(s), who are presented in the context of great historical events of the past.
Some consider every LONG film or every BIG_BUDGET film an epic! This is very much disputed. For those films, see the up-and-comming list http://listsofbests.com/movies longer than 3 hours!
I have at first deleted “Jurassic Park”, “Star Wars” “Dune” here. Although they are all brilliant they are surely of their different own category: “Science Fiction”.
This is an open list, please add those that might be missing. Also I’m not sure about the directors and versions, please indicate/fix any errors detected.