Clarence Mattei (November 13, 1883 – April 2, 1945) was an American portrait painter.
Mattei was born on November 13, 1883, in San Luis Obispo County, California. His dad Felix was an immigrant from Switzerland who first managed a hotel in Cayucos in the past founding Mattei's Tavern in Los Olivos. Mattei was trained in Paris.
Mattei became an oil painter as with ease as a black and white sketcher, with studios in New York and in Santa Barbara, California. Over the course of his career, he did hundreds of portraits.
Mattei married Merle Wilhoit. He died on April 2, 1945, in Santa Barbara, at age 61. His con can be seen at the Santa Barbara Historical Museum.