President of the American Watercolor Society from 1959 through 1986, Mario Ruben Cooper (1905 – 1995) authored multiple how-to books on the challenging medium, and often worked in watercolor for his commercial illustration assignments, unlike so many contemporaries working in oils or gouache. Born in Mexico City, Cooper grew up In Los Angeles, later studying on the east coast at Columbia University and the Grand Central School of Art.
His commercial career flourished through the 1930’s and early 1940’s with covers and interior story illustrations for Collier’s, Esquire and other glossies, which included multiple Agatha Christie mysteries and hard-boiled crime fiction thrillers. After WWII he taught at the Pratt Institute, then was assigned to document the history of American aviation for the military, many of his pieces from that era still in the Pentagon’s collection. Cooper is a Society of Illustrators Hall of Fame inductee.