On Tuesday, just one day before her son David Letterman’s 70th birthday, Dorothy Mengering died peacefully at home at the age of 95. Over the years, Mengering became a beloved fixture of her son’s legacy in late night, beginning with her phone calls to Dave on NBC’s Late Night. Her first on-air appearance came in 1986, when Letterman still aired on his old network—but she became especially well-known after Letterman’s move to CBS in the early 90s.

On CBS’s Late Show, Mengering served as a recurring Winter Olympics correspondent, traveling to Lillehammer, Norway, Nagano, Japan, and Salt Lake City, Utah, to cover the snowy ceremonies. She also made remote appearances from her home on Thanksgiving, when Letterman would try to guess what kinds of pie she had made that year; winsomely delivered Top 10 lists, which usually razzed her son; and paid regular Mother’s Day visits. Throughout her appearances, she forged a comedic legacy of her own—and even got a book deal along the way. Although her son left the air two years ago, Mengering’s death comes as a blow to many of Letterman’s most adoring fans. Here, Vanity Fair looks back at some of her most charming appearances.

First On-Air Appearance, Late Night, 1986

Before the first commercial break on this special episode, Letterman tried to embarrass Mengering by having her shout at pedestrians from a window. Afterward, Letterman asked her with a grin, “Did that just embarrass you to tears?” Her delightfully “mom”-like, deadpan response—”No, David.”—was pretty typical of their on-screen interactions to come.

“Do you know a guy in Indianapolis named Sid Tuchman?”, Late Night, 1990

In a moment of sheer serendipity, Letterman once called a man named Sid Tuchman by mistake while trying to reach his mother. When he finally reached Dorothy, Letterman asked, “Mom, do you know a guy in Indianapolis named Sid Tuchman?” When she said, “Yes,” he lost it, dropping the phone and fanning himself with one of his note cards. Once he’d regained his composure, he got back to joshing her: “O.K., Mom, we’ll just keep rolling here. What two people do in the Midwest is your business.” From there, it was a typically delightful phone call between mother and son.

On YouTube, poster Mitch Tuchman claims, “On July 31, 1990, Dave Letterman called my dad by mistake when he was trying to call his mom in Indianapolis. I can assure you, this was a complete ad lib by Letterman. He woke my dad up from his daily 4 P.M. afternoon nap (they were taping the show in the afternoon in New York). The reason his mom knew Sid, was that Sid had 40 dry cleaning stores around Indianapolis called ‘Tuchman Cleaners.’ Everyone in town knows him! Letterman was right . . . the lawyers did call my dad the following day. But there was no way Sid was going to sue Dave. By the same token, I hope the network doesn’t threaten to sue me for putting this video up for the public as one of the funniest Letterman bits ever!”

A Thanksgiving Phone Call, Late Night, 1991

On Late Night, Letterman made it a habit to call his mother on air. In this Thanksgiving episode, Letterman tried to guess all of the items on Mengering’s menu, and to guess the weight of her turkey. Even when Mengering wasn’t physically present, the dynamic she had with her son was magnetic; fans couldn’t get enough of the way the two teased one another. (Their interaction begins at the 10:37 mark.)

Norway’s Winter Olympics, Late Show, 1994

Mengering was naturally unassuming—which made her the perfect foil for her boisterous son, as seen in this clip, in which Mengering describes her experience lunching on reindeer steak in Norway. When Letterman asks what sides accompanied the meal, she replied, “Potatoes are big here”—to which her son quipped, “Oh? How big do they get, mom?”

Afterwards, he mentioned that they’d just had a shaved dog on the show, asking Mengering, “What do you think of that?” Her response drew big cheers: “It’s too cold for that, David!” (Fast forward to 24:33.)

Japan’s Winter Olympics, Late Show, 1998

Mengering found herself abroad again for the games four years later—but when Letterman asked her to describe the opening ceremonies and how they stacked up against Norway’s, her own son betrayed her by revealing that she was participating in a TV lie.

“The ceremonies were just beautiful, as always,” Mengering said, adding, “You can’t compare them. Each one is unique in its own way. Each country does its own thing.”

“Let me tell you something, ladies and gentlemen,” Letterman said. “This is my mother now, being a sport, playing along and lying, because the opening ceremonies have not yet taken place. I’m telling you, Mom—you could have a career in television!”

“Guess the Pie,” Late Show, 1998

One gambit Letterman loved was doing a remote segment from his mother’s house on Thanksgiving, during which he would try to guess what kind of pies she had made that year. Although Letterman appeared stumped, his bandleader, Paul Shaffer, was able to get it on the first try: rhubarb. The second pie, of course, was pumpkin.

Dave’s Mom Does the Top 10, Late Show, 2005

Another one of Mengering’s talents was tackling Letterman’s Top 10 list on special occasions—including on her 84th birthday in 2005. The subject? “Things I Have Learned in My 84 Years.”

In order (emphasis ours):

1. In a pinch, vanilla extract will give you a good buzz.
2. Think twice before getting a Robert Wagner tattoo.
3. You can kill a man with two fingers, applied swiftly to the Adam’s apple.
4. Male figure skaters are usually gay.
5. Kids don’t listen to parents when it comes to advice on hairpieces.
6. You’re not fully clean unless you’re zestfully clean.
7. With a color printer, you can easily make counterfeit Meineke gift certificates.
8. Never give a bookie your home phone number.
9. For sheer entertainment, you can’t beat Vince Vaughn and Owen Wilson in Wedding Crashers, in theaters now. I just made $1,000 for saying that.
10. It’s hard having a son who looks older than you.