Robert William Vonnoh (September 17, 1858 - 1933) was an American Impressionist painter known for his portraits and landscapes.
He studied in Paris under Gustave Boulanger and Jules Joseph Lefebvre. He taught at the Cowles Art School in Boston (1884-1885), at the School of the Museum of Fine Arts, Boston (1883-1887), and at the Pennsylvania Academy of the Fine Arts (1891-1896).
Vonnoh became a member of the National Academy of Design in 1906.
His wife Bessie Potter Vonnoh (1872-1955) was a sculptor.