“Pac Man Fever” and mullets, Milli Vanilli and Rambo, menacing laugh tracks and Rocky sequels – the ‘80s were a hellish period even if we overlook political nightmares like Reagan selling weapons to Iran, Lee Atwater’s race-baiting and the rise of suspender-clad Wall Street studs who would repeatedly tank the U.S. economy. There may have been another reasonable response to all of this – in other eras, for instance, some of these things may have provoked outrage or morally focused scorn.

But instead, the default response in the 1980s – by a lot of educated urban and suburban folk, at least – was to throw the head back and laugh. And while he didn’t invent it – irony dates back at least as far as classical Greek drama – the man most responsible for the era’s embrace of the ironic smirk, deadpan laugh and self-mocking indifference is about to end his reign on late-night TV. It is surely David Letterman’s greatest legacy.

Letterman, of course, added a lot to the American lexicon. The Indianapolis-reared weatherman and comedian, who launched “Late Night” in 1982, brought a tougher, more confrontational, sometimes condescending interviewing style to television in the U.S. His show served as an important early forum for comedians like Jerry Seinfeld, Paula Poundstone, Sandra Bernhard, Bill Hicks, Jay Leno, Richard Lewis and many others. He gave people outside the underground comics demimonde their first views of Harvey Pekar; it was also a launching pad of sorts for the comic anarchy of Andy Kaufman. When Paul Shaffer and the World’s Most Dangerous Band were not turning out a bland but spirited kind of go-cat-go mainstream rock music, his show hosted smart or pioneering bands like R.E.M. (“Radio Free Europe”!), Phoenix, the White Stripes, Pixies, Outkast, Interpol, TV on the Radio and on and on (along with some schlock like Matchbox 20).

For those of us who live our lives on the Web, Letterman deserves a nod every time a listicle or Top-10 list comes up. Those half-funny T-shirts you saw around college campuses in the late ‘80s and early ‘90s (“Top 10 reasons to rush my fraternity,” “Top 10 reasons to go to Spring Fling,” etc.) were the pre-Internet attempt to capture the goofy charm of those lists. The online world seems better able to make these funny, but either way, the seeds were planted on “Late Night.” We would not have Buzzfeed without Dave.

His influence on late night television, especially on his former guest Jay Leno, is clear and enduring.

It’s the irony, though, that will last the longest. The smirk we get from contemporary comedians and comic actors – everyone from Jon Stewart to Kristen Wiig to Chris Rock – comes in part from Letterman. “Small Town News” led us right to the Onion. Quentin Tarantino’s films are Letterman with sadism and violence.

But it’s the blank, what-me-worry irony – the lack of outrage or frustration of the kind of we’d gotten from Richard Pryor, the lack of political point of view that we’d gotten from Mort Sahl or ‘70s “Saturday Night Live” – that will live the longest.

And this is where things get tricky. Thomas Frank has written how “Animal House” (which was set at Dartmouth, breeding ground of felon Dinesh D’Souza and the Dartmouth Review) was not just about a bunch of wild-ass cats like Belushi’s Bluto, but the birth of the coked-up, deregulating bad behavior of the New Right. Letterman, similarly, is not just a funny guy whose show changed the American sense of humor: You can see his sensibility in pernicious figures like the smugly creepy Ted Cruz (who often seems like a bad, misfired Andy Kaufman impersonator) and Sarah Palin (listen to her dismissals of the “lame-stream media”). All of Generation X, wherever across the political spectrum, grew up in the ‘80s and breathed the same air, in which Reagan and Letterman were both cultural fathers.