David Letterman

David Michael Letterman (born April 12, 1947) is an American television host, comedian, writer, and producer. He hosted a late night television talk show 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 6,028 episodes of Late Nightand Late Show surpassing friend and mentor Johnny Carson as the longest-serving late night talk show host in American television history. 1996 Letterman was ranked 45th on TV Guide's 50 Greatest TV Stars of All Time.
Letterman is also a television and film producer. His company, Worldwide Pants, produced his show as well as The Late Late Show with Craig Ferguson and several prime-time comedies, the most successful of which was Everybody Loves Raymond, now in syndication.
Several late-night hosts have cited Letterman's influence, including Conan O'Brien (his successor on Late Night), Stephen Colbert (his successor on The Late Show), Jimmy Fallon, Jimmy Kimmel and Seth Meyers.
Early life and career
Letterman was born in Indianapolis, Indiana. His father, Harry Joseph Letterman (April 15, 1915 – February 13, 1973), was a florist. His mother, Dorothy Marie 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.
He lived on the north side of Indianapolis (Broad Ripple area), not far from Speedway, Indiana, and the Indianapolis Motor Speedway; and 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 age 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 at age 57.

Weatherman

Letterman began his career as a radio talk show host on WNTS (AM) and on Indianapolis television station WLWI (which changed its call sign to WTHR in 1976) as an anchor and weatherman. He received some attention for his unpredictable on-air behavior, which included congratulating a tropical storm for being upgraded to a hurricane and predicting hailstones "the size of canned hams. He would also occasionally report the weather and the day's very high and low temps for fictitious cities ("Eight inches of snow in Bingree and surrounding areas") while on another occasion saying that a state border had been erased when a satellite map accidentally omitted the state border between Indiana and Ohio, attributing it to dirty political dealings. ("The higher-ups have removed the border between Indiana and Ohio making it one giant state. Personally, I'm against it. I don't know what to do about it.") He also starred in a local kiddie show, made wisecracks as host of a late night TV show called "Freeze-Dried Movies" (he once acted out a scene from Godzilla using plastic dinosaurs), and hosted a talk show that aired early on Saturday mornings called Clover Power in which he interviewed 4-H members about their projects.
Morning show
Main article: The David Letterman Show
On June 23, 1980, Letterman was given his own morning comedy show on NBC, The David Letterman Show. It was originally 90 minutes long, but was shortened to 60 minutes in August 1980.The show was a critical success, winning two Emmy Awards, but was a ratings disappointment and was canceled in October 1980.

Late Night with David Letterman
Main article: Late Night with David Letterman
NBC kept Letterman under contract to try him in a different time slot. Late Night with David Letterman debuted February 1, 1982; the first guest on the first show was Bill Murray. Murray later went on to become one of Letterman's most recurrent guests, guesting on the show's 30th anniversary episode, which aired January 31, 2012 and on the very last show, which aired May 20, 2015. The show ran Monday through Thursday at 12:30 a.m. Eastern Time, immediately following The Tonight Show Starring Johnny Carson (a Friday night broadcast was added in June 1987). It was seen as being edgy and unpredictable, and soon developed a cult following (particularly among college students). Letterman's reputation as an acerbicinterviewer was borne out in verbal sparring matches with Cher (who even called him an asshole on the show), Shirley MacLaine Charles Grodin, and Madonna. The show also featured comedy segments and running characters, in a style heavily influenced by the 1950s and 1960s programs of Steve Allen.
Reference
https://en.wikipedia.org/wiki/David_Letterman