Guess is an American name-brand clothing line. Guess also markets other fashion accessories besides clothes, such as watches and jewelry.

Guess was founded by Georges, Armand, Paul, and Maurice Marciano, four brothers born in Ouarzazate, Morocco. They moved to California in 1977 and founded the company in 1981. Seed money to start the business came from the Nakash family, owners of the Jordache denim empire. Their first product was a three-zipper style of jeans they named "Marilyn" (Style # 1015).

Their advertising campaigns began in 1982, and they introduced their iconic black-and-white ads in 1985. The ads have won numerous Clio Awards. Their fashion models have included a number of widely-recognized supermodels, many of whom first achieved prominence via the ad campaigns.

In the 1990s, they also had a division called Guess Home, which featured youthful, upscale bedding collections (Guess was the first company to package each sheet, duvet and pillowcase pair in packaging actually made from sheeting material, which was a clever way to show what the pattern really looked like) as well as a number of innovative towel collections.