Kasper Gutman, known as Casper Gutman in the novel, is the main antagonist of the 1929 Dashiell Hammett novel The Maltese Falcon, it's 1931 film adaptation of the same name; as well as John Huston's 1941 remake, along with his sidekicks Joel Cairo and Wilmer Cook. He is also called 'The Fat Man' due to his obesity, and he appears to have some sort of criminal background and for several years he has been hunting the Maltese Falcon: the McGuffin that is extremely valuable as it has jewels and gems under its skin.
He was portrayed by Dudley Digges in the 1931 film, and by Sydney Greenstreet in the 1941 film.