Letterman may refer to:
- Letterman (sports), a classification of high school or college athlete in the United States
- David Letterman (born 1947), American television talk show host
- Late Show with David Letterman, talk show that has aired on CBS since 1993
- Late Night with David Letterman, talk show that aired on NBC from 1982 to 1993
- Jonathan Letterman, American surgeon known as the "Father of Battlefield Medicine"
- William Henry Letterman, co-founder of the Phi Kappa Psi fraternity and brother of Jonathan
- Letterman Army Hospital, hospital operating from 1898 to 1995 on the Presidio of San Francisco, named after Jonathan Letterman
- Letterman Digital Arts Center, the home of several Lucasfilm units, located on the site of the former Letterman Army Hospital
- The Adventures of Letterman, segment on the children's show The Electric Company
- The Lettermen, musical group
- Mail carrier