He became a late night TV sensation during the 1982 debut of NBC's Late Night with David Letterman, and later hosted The Late Show with David Letterman. In 2014, he announced that he would retire from The Late Show in 2015.
He worked as a weatherman for AM radio station WNTS and anchored on Indianapolis television station WLWI.
Although he registered for the draft during the Vietnam War, he did not fight because he received a draft lottery number 346 (out of 366).
He married Michelle Cook on July 2, 1968, and after their divorce on October 13, 1978, he married Regina Lasko on March 19, 2009. He and Regina had a son named Harry in 2003.