Robert Nelson Cornelius Nix Sr. (August 9, 1898 – June 22, 1987) was an American politician who served in the United States House of Representatives from 1958 until 1979.

[1] Born in Orangeburg, South Carolina, he attended Townsend Harris High School in New York City and graduated from Lincoln University (Pennsylvania) in 1921.

In 1958, he defeated two opponents in a special election to fill a congressional vacancy left by Earl Chudoff in the House of Representatives.

He worked for the passage of the landmark legislation promoting the American Civil Rights Movement and privately sought to prevent the House from denying Rep. Adam Clayton Powell his seat in 1967.

In 1962, he became the first member of congress to knowingly meet with gay activists, when he invited Frank Kameny to his office.