Lett may refer to:
- Lett, archaic word for Latvian
- Lettish, another name for the Latvian language
Lett as a surname may refer to the following:
- Barbara Lett-Simmons (born 1927), American politician
- Benjamin Lett (1813–1858), Irish-Canadian filibusterer
- Dan Lett, Canadian actor
- David Lett (born 1939), founder and winemaker for The Eyrie Vineyards in Oregon
- Evelyn Lett (1896-1999), Canadian women's rights pioneer
- Leon Lett (born 1968), former American Football defensive tackle
- Michael Lett (born 1987), Rugby League player who plays for the Sydney Roosters in the National Rugby League (NRL) competition
- Sherwood Lett (1895–1964), Canadian soldier, lawyer, diplomat, and jurist
- Lett's Brewery (officially Mill Park Brewery), a beer manufacturer based in Enniscorthy, County Wexford, Ireland