Giuseppe Guglielmo Umberto Caselli (July 5, 1893 – December 19, 1976) was an Italian painter. He studied under Felice Del Santo and Antonio Discovolo. In 1913, Caselli was imprisoned in a concentration camp in Austria. After that, he studied at the Academy of Fine Arts in Florence. In 1938 he participated in the Premio del Golfo (Gulf Award), organized by Filippo Tommaso Marinetti.
Caselli was one of the best known painters from La Spezia. He painted thousands of works during his long career. In his paintings, Caselli showed the life of La Spezia. He painted the life in the Cinque Terre (Five Lands), a portion of coast on the Italian Riviera.