Lost can refer to:

• A hamlet in Scotland; see: Lost, Scotland

• A hip hop album; see: Lost (album)
• An acronym for the Law of the Sea Treaty.
• A movie released in the 1950s, known as Tears for Simon in the US. See Lost (movie)
• A short-lived reality television program on NBC in the USA. See Lost (2001 television series)
• A 2004 television show on ABC from Alias creator J.J. Abrams. See Lost (2004 television series).

LOST (all capitals) refers to Mustard gas