In pictures: Conan O'Brien's late-night career

Conan O'Brien is seen backstage on the set of his show "Conan" in 2019. He's been a late-night host for nearly 30 years.

O'Brien is the guest as he appears on "The Tonight Show with Jay Leno" in 1996. In 2009, O'Brien would replace Leno as "The Tonight Show" host — at least for a short while.

O'Brien does a skit with his longtime show sidekick, comedian Andy Richter, in 1996. Richter has been a part of O'Brien's show for much of his late-night run.

O'Brien delivers a monologue as he hosts an episode of "Saturday Night Live" in 2001. Before he became famous, O'Brien was a writer for the show.

O'Brien warms up the crowd at one of his "Late Night" tapings.

O'Brien takes a photo of Microsoft co-founder Bill Gates during the Consumer Electronics Show in 2005.

O'Brien hands a Valentine's Day present to Finnish President Tarja Halonen as he visited the presidential palace in Helsinki in 2006. O'Brien's resemblance to Halonen became a recurring bit on his show, and he eventually traveled to meet her and do a special episode from Finland.

O'Brien jokes around with fellow talk-show hosts Stephen Colbert, left, and Jon Stewart during a "Late Night" episode in 2008.

O'Brien does a Christmas segment with boxing legend Mike Tyson and longtime show performers Andy Richter and Max Weinberg in 2009. O'Brien replaced Jay Leno as host of "The Tonight Show" earlier that year, but he didn't stay there for long.

O'Brien is joined by Triumph the Insult Comic Dog, one of his show's most iconic characters, in 2009.

O'Brien's last episode of "The Tonight Show" aired on January 22, 2010, less than a year after he started. With ratings flagging, NBC wanted to move Jay Leno back into late night and push "The Tonight Show" to a later time slot to accommodate Leno's new show. O'Brien refused the time change and left. But during his farewell show, O'Brien had a hopeful message for his audience. "All I ask is one thing, and I'm asking this particularly of young people that watch: Please do not be cynical," he said. "I hate cynicism. For the record, it's my least-favorite quality — it doesn't lead anywhere. Nobody in life gets exactly what they thought they were going to get. But if you work really hard and you're kind, amazing things will happen."

O'Brien appears on Letterman's show in 2012. They discussed O'Brien's short-lived stint as host of "The Tonight Show" and had some fun at Jay Leno's expense.

O'Brien jokes with President Barack Obama as he hosted the White House Correspondents' Association dinner in 2013. It was O'Brien's second time hosting the event. He also hosted in 1995.

O'Brien hosts the MTV Movie Awards in 2014.

O'Brien wears a bomb disposal suit as he taped episodes of his "Conan" show in Qatar in 2015. O'Brien traveled to Qatar along with first lady Michelle Obama, and he also entertained US troops who were stationed there.

O'Brien dances in Cuba in 2015. He became the first American late-night host to do a show in Cuba in more than 50 years.

O'Brien speaks on stage during a gala tribute to comedian Steve Martin in 2015.

O'Brien poses for a photo with journalist Jorge Ramos as they walk in Mexico City in 2017. O'Brien taped an episode of his show in Mexico to "do something positive" after the tensing of US-Mexico relations.

O'Brien fist-bumps basketball legend Shaquille O'Neal during a Turner Upfront show in 2017.

O'Brien tapes a segment while visiting Japan in 2018.

O'Brien goofs around with Stephen Colbert while appearing on "The Late Show" in 2019.

O'Brien visits Ghana with his show in 2019.

O'Brien does a segment about "The Two Popes" in 2020.

O'Brien's last "Conan" show will air on June 24, 2021. The show has been on TBS since 2010.