William Louis Sonntag Sr. (1822–1900) was an American landscape painter.

[1] Born near Pittsburgh, Pennsylvania in 1822, he traveled to Cincinnati, Ohio, at the age of 21 and perfected his technique.

Becoming an established and highly regarded landscape artist, he began making trips to Florence, Italy in 1853.

In 1856, Sonntag permanently moved to New York to become a leading painter of Romantic landscapes of several scenes from his travels in Italy.

Grand Canyon, Yellowstone River, Wyoming, for example, is a landscape that Sonntag never traveled to.