David Michael Letterman (born April 12, 1947) is an American television host, comedian, writer, producer, and auto racing team owner. He hosted late-night television talk shows for 33 years, beginning with the February 1, 1982, debut of Late Night with David Letterman on NBC and ending with the May 20, 2015, broadcast of Late Show with David Letterman on CBS. In total, Letterman hosted 6,080 episodes of Late Night and Late Show, surpassing his friend and mentor Johnny Carson as the longest-serving late-night talk show host in American television history.

Letterman is also a television and film producer. His company, Worldwide Pants, produced his shows as well as The Late Late Show and several primetime comedies, the most successful of which was the CBS sitcom Everybody Loves Raymond. Several late-night hosts have cited Letterman's influence, including Conan O'Brien, Jimmy Fallon, Seth Meyers (each of whom succeeded Letterman on Late Night), Stephen Colbert (his successor on The Late Show), Jimmy Kimmel, and Jon Stewart. Since 2018, he has hosted the Netflix series My Next Guest Needs No Introduction with David Letterman.

Letterman was born in Indianapolis, Indiana, on April 12, 1947, and he has two sisters, one older and one younger. His father, Harry Joseph Letterman (April 15, 1915 – February 13, 1973), was a florist. His mother, Dorothy Marie Letterman Mengering (née Hofert; July 18, 1921 – April 11, 2017), a church secretary for the Second Presbyterian Church of Indianapolis, was an occasional figure on Letterman's show, usually at holidays and birthdays.

Letterman grew up on the north side of Indianapolis, in the Broad Ripple area, about 12 miles (19 km) from the Indianapolis Motor Speedway. He enjoyed collecting model cars, including racers. In 2000, he told an interviewer for Esquire that, while growing up, he admired his father's ability to tell jokes and be the life of the party. Harry Joseph Letterman survived a heart attack at the age of 36 when David was a young boy. The fear of losing his father was constantly with Letterman as he grew up. The elder Letterman died of a second heart attack in 1973 at the age of 57.

Letterman attended his hometown's Broad Ripple High School and worked as a stock boy at the local Atlas Supermarket. In an interview, he said the first concert he attended was by The Beach Boys at the Indiana State Fairgrounds Coliseum, when he was 17. According to the Ball State Daily News, he originally wanted to attend Indiana University, but his grades were not good enough, so he instead attended Ball State University in Muncie, Indiana. He is a member of the Sigma Chi fraternity, and graduated in 1969 from what was then the Department of Radio and Television. A self-described average student, Letterman later endowed a scholarship for what he called "C students" at Ball State. Though he registered for the draft and passed his physical after graduating from college, he was not drafted for service in Vietnam because he received a draft lottery number of 346 (out of 366).

Letterman began his broadcasting career as an announcer and newscaster at the college's student-run radio station—WBST—a 10-watt campus station that is now part of Indiana Public Radio. He was fired for treating classical music with irreverence. He then became involved with the founding of another campus station—WAGO-AM 570 (now WCRD, 91.3).

He credits Paul Dixon, host of the Paul Dixon Show, a Cincinnati-based talk show also shown in Indianapolis while he was growing up, for inspiring his choice of career:

I was just out of college [in 1969], and I really didn't know what I wanted to do. And then all of a sudden I saw him doing it [on TV]. And I thought: That's really what I want to do!