George Willis Ritchey (December 31, 1864 – November 4, 1945) was an American optician and telescope maker and astronomer born at Tuppers Plains, Ohio.
Ritchey was educated as a furniture maker. He coinvented the Ritchey-Chrétien(R-C) reflector telescope along with Henri Chrétien. The R-C prescription remains the predominate optical design used by most all major astronomical observatories and space telescopes.
He played a major role in designing the mountings and making the mirrors of the 60-inch (1.5 m) and 100-inch (2.5 m) telescopes at Mount Wilson Observatory. He worked closely with George Ellery Hale.
The last reflector telescope produced by Ritchey remains in operation at the U.S. Naval Observatory Flagstaff Station in Flagstaff, Arizona.
Craters on Mars and the Moon were named in his honor.