| Image Name: | WilliamCotter.jpg |
| State: | Connecticut |
| District: | 1st |
| Party: | Democratic |
| Term Start: | January 3, 1971 |
| Term End: | September 8, 1981 |
| Preceded: | Emilio Q. Daddario |
| Succeeded: | Barbara B. Kennelly |
| Birth Name: | William Ross Cotter |
| Birth Date: | 18 July 1926 |
| Birth Place: | Hartford, Connecticut, U.S. |
| Death Place: | East Lyme, Connecticut, U.S. |
| Alma Mater: | Trinity College |
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 then served as Connecticut's deputy insurance commissioner from 1957 to 1964 and as insurance commissioner from 1964 through 1970.
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.