Don O'Neill (1924–2007) was a United States watercolor artist most noted for his depictions of historic downtown Riverside, California. An architect by trade, he began painting in the 1960s, and eventually became Riverside's premier watercolorist. O'Neill became the first resident of Southern California's Inland Empire to be accepted into the American Watercolor Society.His grandchild is currently in charge of managing his artwork, at Don O'Neill's request.