The fiance and I have been watching The Americans, and as the starting point is '81 (right after Reagan is inaugurated) I was reminded what a great year it was for genre films. Just start with a few that instantly come to mind.
Two directors return to glory after unmitigated disasters that could have easily destroyed them with films that would go on to influence others (and in showbiz terms, launch countless knock-offs) for years to come. Steven Spielberg with Raiders of the Lost Ark and John Boorman with Excalibur.
John Landis directs, for my money, the defining film of his career (whose MO of blending horror and comedy would be repeated for decades to come) An American Werewolf in London. Not to mention, Joe Dante's "other great werewolf movie of '81" The Howling.
So, so many others I'm forgetting here...