For a generation of late-night TV watchers, Paul Shaffer will forever be known as the bald, bespectacled band leader and sidekick of David Letterman over the span of 33 years and two different talk shows.

While that's a proud legacy to carry, it woefully undersells the career of a man who should be considered a comedy superstar. Before—as well as during—his time with Letterman, Shaffer was also at ground zero for a handful of some of the biggest comedy institutions of the '70s and '80s. He's like the Zelig or Forrest Gump of late 20th century humor.

To use his lingo, Paul Shaffer is one hip, funny cat.

As Dave and Paul ride into the sunset this week (the final Late Show With David Letterman airs May 20), we take a look at Shaffer's other significant contributions to American comedy.

National Lampoon Radio Hour

Shaffer began combining his comedic and musical skills in the mid-'70s on this spinoff endeavor from the National Lampoon magazine. During this era, the Lampoon—along with The Second City improv theater—was one of the major incubators for the next generation of comic talent that would hit the scene in the late '70s and throughout the 1980s. As a way to expand its brand, the Lampoon created the National Lampoon Radio Hour, a weekly syndicated radio show, as well as a handful of comedy albums.

It was during his time with the Radio Hour that Shaffer initially met and worked with such legends as Dan Aykroyd, John Belushi, Bill Murray and Christopher Guest. In fact, he co-wrote this classic holiday song, "Kung Fu Christmas," with the latter two.

Saturday Night Live

Although Shaffer was initially hired on as a musician for Saturday Night Live's band when the show started, he eventually was elevated to featured cast member status in the fifth season (1979-80). Unfortunately, Shaffer's time in the spotlight came as the show's first golden age was fizzling out, and his comic contributions to SNL, such as impersonating music Don Kirshner (see video below), have been largely forgotten.

Shaffer does hold two legendary Saturday Night Live distinctions, though: He was the pianist for Bill Murray's lounge singer bits (even during the show's recent 40th anniversary special), and in 1980, he was the first in a select and infamous group of SNL cast members to say "fuck" during a live show broadcast (he was supposed to use the word "flogging"). 

The Blues Brothers

Who's that young-looking cat circled in red? Yup, that's Paul Shaffer from the Blues Brothers's 1978 "Briefcase Full of Blues" album. Shaffer—listed as Paul "The Shiv" Shaffer—is credited with keyboards and backing vocals on the album. (Atlantic Records) 

On a recent episode of the Showtime series Inside Comedy, Dan Aykroyd labeled Shaffer as "a great contributor to Canadian and world humor" and called him one of the main Blues Brothers. Shaffer worked with Aykroyd and John Belushi to develop the music for the Blues Brothers act, as well as the duo's 1978 album, Briefcase Full of Blues.

But Shaffer was left out of the 1980 Blues Brothers movie because Belushi didn't like all the time Shaffer spent working on fellow SNL cast member Gilda Radner's album at the same time. Aykroyd made it up to Shaffer by giving him a role in Blues Brothers 2000. Or maybe Aykroyd was still punishing him for working on Radner's album. It's hard to tell.

Mr. Mike's Mondo Video

 That's quite the cast for "Mr. Mike's Mondo Video." And yes, that grainy screencap is, indeed, Paul Shaffer. (New Line Cinema)

This film sounds like what happens when a group of friends and colleagues get a little too much money and a little too much fame and decide to indulge in all their dark and creative excesses. But 1979's little-seen Mr. Mike's Mondo Video is a collection of wildly unhinged, often hilarious, anarchic comedy pieces, orchestrated by SNL writer Michael O'Donoghue, probably the craziest, most innovative writer in the show's history. 

So how does Shaffer fit in? He was the film's musical director, and he pops up briefly as an organist in this bizarre Church of Jack Lord bit with Dan Aykroyd. As musical director, it's not clear if Shaffer had a hand in this brilliant sketch with Sid Vicious singing (sort of) "My Way."    

Steve Martin's Best Show Ever

By 1981 standards, that dog special-effects makeup Paul Shaffer's sporting is cutting edge. (NBC) 

Never let it be said that Paul Shaffer doesn't have comedic range. How many other actors can nail a comic performance while in full-on dog makeup? Yup, that's Shaffer as Jo Jo the Dog-Faced Boy in the "Elephant Guy" sketch from Steve Martin's 1981 NBC special. Shaffer doesn't have a huge role, but considering how much could go wrong dressed as a beagle and playing opposite Steve Martin while he's wearing ridiculous elephant prosthetics and snifting brandy through a plastic trunk, he acquits himself quite admirably.     

This Is Spinal Tap

Shaffer's best comedic turn is in 1984's This Is Spinal Tap as Artie Fufkin, the inept Polymer Records promoter. He plays the role for laughs, but he also brings an authenticity to the performance. You can almost tell Shaffer is pulling out the worst qualities of slimy music promoters he'd encountered over the years in order to portray Fufkin. 

But don't take my word for it. Just watch this classic scene.  

Bill Murray's Upcoming Netflix Christmas Special

I suppose this is a cheat since this special hasn't aired yet (and probably isn't even complete). This musical show, directed by Sofia Coppolla, could well be the result of prayers that should never have been answered.

But George Clooney recently revealed that he performs a duet with Shaffer and takes a sleigh ride with Miley Cyrus as part of this epic program. And it also stars Amy Poehler and Maya Rudolph. Hell, this might not be any good, but it'll definitely be worth watching.

Plus, mentioning the special gives me an excuse to run a classic clip of Shafffer providing keyboard accompaniment to Murray's Nick the Lounge Singer.

BONUS: Was Shaffer Almost George Constanza?

TV history could have gone in a different direction if Paul would've just returned Jerry's phone call. (Sony/NBC)

According to Shaffer, he was Jerry Seinfeld's first choice to play the role of George Constanza. Seinfeld apparently left a phone message about it that Shaffer never returned. So the role eventually went to Jason Alexander.

Recently, however, Seinfeld discredited Shaffer's account of the story on Access Hollywood, claiming he doesn't know how Shaffer came up with that idea. But it's hard to tell if Jerry's being serious or making a joke at Shaffer's expense.

It doesn't really matter, though, if Shaffer was almost George. It would've been just one more notch on the man's already impressive comedic bedpost.