William Ross Cotter (July 18, 1926 – September 8, 1981) was an American politician and Democratic member of the United States House of Representatives from Connecticut.

He was born in Hartford, Connecticut and graduated from Trinity College in 1949.

In 1953, he was elected to the city's court of common council and from 1955 to 1957 served as an aide to Governor Abraham Ribicoff.

He was elected as a Democrat to the Ninety-second and to the five succeeding Congresses and served from January 3, 1971, until his death from pancreatic cancer at his sister's home in East Lyme, Connecticut, on September 8, 1981, aged 55.

[1] In 1982, the William R. Cotter Federal Building at Hartford was named in his honor.