Watch Jimmy Fallon’s Heartfelt Tribute to David Letterman

Jimmy Fallon got serious for a moment Monday night, delivering a heartfelt message to the retiring David Letterman: “Like every kid who grew up watching him, [I] will miss him.”

Fallon became particularly emotional as he remembered Letterman’s reaction following 9/11.

“He’s always just there when you need him. I remember after 9/11, we needed somebody,” Fallon said. “The city was in shock. We’re all looking for answers. We wanted to see what Dave had to say and we looked at him to say something.”

“He said, ‘There is only one requirement for any of us and that is to be courageous, because courage, as you know, defines all other human behavior.’ We needed that. David Letterman is courageous. Have a nice retirement, Dave.”

Letterman, whose last show will air May 20, was the first late-night host to return to air after the terrorist attacks, for a somber taping of his show that featured Paul Shaffer leading the CBS Orchestra in a rendition of John Lennon’s “Imagine.”

This article originally appeared on People.com.

Bill Murray is Dave’s first guest (1982)

For Letterman, Murray has dressed like Liberace, a Kentucky Derby jockey and a Renaissance fop. His first visit set the tone of the show when, after a long rant in which Murray decried the host’s “mind games,” Letterman responded, “Now that you’re well-known, is it harder to be funny?”

Andy Kaufman challenges wrestler Jerry Lawler to a match (1982)

In a hoax bit, comedian Kaufman got pro wrestler Lawler to slap him in the face as Letterman smirked behind the desk. The stunt confirmed Dave’s status as a comedy chaos magnet—a master at remaining calm while hysteria swirled around him.

Dave gets dunked in a suit made of 3,400 Alka-Seltzers (1984)

What some do for science, Dave did for comedy. With a snorkel and goggles in place, Dave was dunked into a fizzy experiment in laughter. He’s helpless in his harness, floating in an effervescent water tank surrounded by the volcanic chaos of bubbles. The experiment was duplicated with the likes of sponges, marshmallows and velcro, showing how far Dave would go for a laugh.

The very first top 10 list (1985)

“Heats.” “Rice.” “Moss.” These were the initial entries in the show’s first Top 10 list, “Things That Almost Rhyme With Peas.” Sometimes presented by politicians, celebrities, sports champions and everyday heroes, the lists—more than 4,600 of them—became Letterman’s signature bit.

Cher calls Dave an a–hole (1986)

Dave’s meta-deconstruction of the late night form led to uncomfortable truths — such as in this segment, where an interview with Cher centered on why it took four years for her to agree to appear on the show. Her casual reasoning — “because I thought you were an a–hole” — became part of the show’s disarming folklore.

Madonna won’t stop stop cursing (March 31, 1994)

Letterman often had a flirty effect on female guests, causing many to leave filters at the door. Here, Madonna and Dave giggled and teased, discussing their underwear and making innuendos. Madonna sweetly told Dave he was a “sick f-ck.” Never has that term sounded quite so loving.

Drew Barrymore flashes Dave for his birthday (April 12, 1995)

In a ’90s version of Marilyn Monroe’s “Happy Birthday, Mr. President,” a 20-year-old, braless Barrymore surprised Dave with a dirty dance on his desk, followed by lifting her shirt. Dave’s reaction—confused but joyful surprise—contributed to the buzz.

Dave gets personal (2000 & 2009)

It’s one thing to be a great host with a knack for comedic moments. It’s another entirely to tap into the national psyche. Dave was long regarded as the king of irony, but that died in 2000, when he dropped all comedic facades to pay tribute to the surgical team that saved his life. It was a rare but powerful moment when Dave the host became Dave the man—a feeling that would be replicated as his messy personal cheating scandal went public nine years later—and his brittle realness drew us even closer to the legend we thought we knew.

Dave gives a heartfelt post-9/11 monologue (2001)

The first late-night host to return to TV, Letterman gave viewers real catharsis following a national tragedy. His eight-minute introduction was halting, honest and vulnerable, tapping into our collective fear and sadness. By the end, he also provided what we needed most: courage and hope.

Joaquin Phoenix is bizarre and rambling (Feb 2009)

Phoenix devised a meta-hoax that found him growing a long beard and claiming to have left acting for hip-hop. Included in this, for reasons not quite clear, was appearing on Letterman like he had no idea what was happening around him. Letterman fired questions at Phoenix despite the guest’s inability to string together a sentence. Ending the interview with, “Joaquin, I’m sorry you couldn’t be here tonight,” cemented the segment as a classic.