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David Letterman steps down from "The Late Show" Wednesday night after 33 years in late night.

Letterman has been winding things down with some of Hollywood’s biggest names who were his favorite guests over the years, but we’re sending him off with some smaller moments that made him and his show so special.

The comedian

Like his hero, Johnny Carson, Letterman played a big role in the careers of young comedians. Los Angeles-based stand-up comic Paul Morrissey tells us his story of getting bumped from Letterman:

His appearance on the show:Paul Morrissey on Letterman

The musician

Letterman's show was also a platform for musicians, many of whom were just on the verge of breaking out. Dave's favorites made repeat appearances over the years, and Los Lobos were one of those groups that came back multiple times. Band member Louie Perez says that Dave and Co. were always on point — but that didn't always extend to the other guests on the show.

The assistant and future comedy writer

The show was also a proving ground for generations of comedy writers. Comedy writer Caissie St. Onge, now an executive producer on Bravo's "Watch What Happens Live," got her start with Letterman in his early days at CBS, first as an intern and then an assistant in his office.

St. Onge says that, when she started, she was a "feral animal" as far as not knowing the business, and Letterman trained her in the ways of late night. He was also what St. Onge describes as an "old school" guy, from thank yous to everyone to walking on the street side when walking with a woman to protect her.

Her duties included writing letters for Dave, which served as comedy training, including once when they were trying to book an actor who’d been hard to get.

"He just was really old school about corresponding with people, so he was writing letters all the time," St. Onge says. "So once I became comfortable just writing a letter from him or suggesting the way a letter should go, then I said, 'Well, can I try to make these funny since they're coming from you?' And he said, 'Well, you can try, but they really have to be funny.'"

St. Onge was an aspiring comedy writer, and she used the opportunity to hone her comedy writing. Letterman would personally approve all of his correspondence, circling things and making correction notes.

"So I just started to try to put little jokes in these letters, and he would sit down with a red pen and go over them, and say, 'Well, it'd be funnier if you put this word at the end, and you don't need this part, this is just clearing your throat, and you can take this part out and get right to the punchline.'"

That hard-to-book actor: Nicolas Cage, whose "Leaving Las Vegas" was getting Oscar buzz at the time. He'd already declined to be on the show several times, and while they thought they had him now, he was showing reluctance about actually showing up.

"So the producers came to Dave and said 'Maybe you could just send him a note to shore up this booking, and make sure that we get him.' So Dave was like, 'Ugh, he's just going to cancel again, you know?'"

Letterman's office often was sending out letters asking people to be on the show and thanking others for appearing, so St. Onge asked Letterman what should be in the letter. He didn't have anything in mind, so St. Onge took the initiative to write something up herself.

"It was an attempt at a joke, and I thought it was brilliant at the time. I realize now that it's not, but I wrote, 'Dear Nicolas, Looking forward to your appearance on the show. Stop being such a woman. Your friend, Dave.'"

She put the letter in a pile to be signed by Letterman, and the letter was signed without any corrections. St. Onge made a copy and sent the original off to Cage.

"A few days later Dave was like, 'Um, we still have to write that letter to Nicolas Cage,' and I [said], 'No no, we did it.' And he said, 'What?'"

St. Onge pulled out the copy of the letter and read it to Dave.

"He was just like, 'Oh my God! We can not have sent this! This is not a good thing to have said to this movie star that we're trying to get on the show!' And I [said], of course, but he signed it!"

Letterman said that it must have slipped through and that he hadn't been paying attention, but that St. Onge needed to invoke the assistants code and get that letter back.

"And of course I was tearing apart the mailroom, hoping it hadn't gone out yet, and of course it had gone out, and so I just thought, 'I'm definitely getting fired.' And then a couple of days later, I got in early, and we received a huge arrangement of roses from Nicolas Cage, saying, 'I'm going to stop being such a woman and come on your show.'"

Cage came on, bringing the letter along. Letterman denied all knowledge of it, saying that it was a forgery.

Nicolas Cage interview on Letterman

To cap off the moment and close the segment, Helen Reddy came out and sang her hit "I Am Woman (Hear Me Roar)," which was part of a running gag on that episode of the show where she kept singing it throughout the episode.

Helen Reddy on the Late Show

St. Onge first interviewed to be an intern on Letterman's show, hoping to land a position interning with the writers, but after being interviewed, she discovered that they'd actually already chosen their intern for the term.

"I was like, 'Why did they do that?!' And [the internship director said] 'They just like to talk to girls, I guess!'"

In the end, St. Onge landed an interview with Letterman's office. She was asked in the interview if she could drive a stick shift, which was one of the key parts of the job — gassing up Dave's car — which she couldn't. She thought that meant she was out of the running, but she ended up getting a call and got the gig.

Letterman's reasoning, according to St. Onge: "He was like, 'Well, you have a weird name, you went to an off-brand college, and I just figured you're going to need all the help you can get.'"

He also said, on the plus side, that she was a smart girl and he figured she could figure the car thing out. St. Onge left to go work on "The Rosie O'Donnell Show" as an actual comedy writer with Dave's blessing, and has taken that Letterman experience with her writing for more shows and landing an Emmy nomination.

St. Onge says she'll miss Letterman being on the air, and that it still feels like it's too soon for him to leave.

"I think he's still really, really funny," St. Onge says. "Anything you see anyone doing in late night television today is a direct result of this show that he and Merrill Markoe, the first head writer of 'Late Night,' basically created. ... So anything that you see today wouldn't be possible, I don't think, because prior to Dave doing 'Late Night,' late night talk shows were just a very different thing."

Letterman also leaves a legacy in how late night comedy and videos you see online are done today, she says.

"I'll see some viral video clip from some show going around, and people are like, 'Did you see this amazing thing that so-and-so did?' And I'll think, 'Oh, Dave did that.'"

And he did it 20 or 25 years ago, St. Onge says. Wednesday night presents one more chance for people to see what Letterman has made a career of, as Stephen Colbert prepares to try to fill a pair of giant, giant shoes.

This story has been updated.