1882-1922. At the age of ten, he won second place for a watercolor he exhibited in the 1892 Dallas Fair. In 1898, he presented a fine pen and ink drawing to his best boyhood friend. Soon after that he presented the family an unusual large colorful painting for their dining room. But as the sales of his works increased, he would have no further need to give them away. He focused on landscapes.

Robert Julian Onderdonk was a member of the Allied Artists of America, Salmagundi Club and San Antonio Art League. His paintings are in the Dallas Museum of Fine Arts, Fort Worth Art Association, Museum of Fine Arts of Houston, San Antonio Museum Association and Stark Museum of Art, Orange, Texas.