C. Willis Damon (1850-1916) was an American architect from Haverhill, Massachusetts.
Damon was born in Pawtucket, Rhode Island in 1850. He was the son of Calvin Damon, a Universalist minister. Around 1856 the family moved to Haverhill. Damon graduated from the architectural program at the Massachusetts Institute of Technology, then only a few years old. Beginning in 1873 he was practicing architecture in Haverhill. He was the city's first college-trained architect. In 1874 or 75 he took his brother, Charles P. Damon (d.1919), as a partner. The firm, Damon Brothers, lasted until 1915, at which point Damon appears to have retired. His brother continued the practice for a few more years, doing only minor work.
Damon was selected as the architect of the 1909 High School (now City Hall), but was ultimately made supervising architect for Kilham & Hopkins of Boston.