Muriel Buck Humphrey (February 20, 1912–September 20, 1998) was the wife of Vice President Hubert H. Humphrey, and a United States Senator. She later remarried and took the name Muriel Humphrey Brown.

Muriel Humphrey served as a Senator from Minnesota. She was born Muriel Fay Buck in Huron, South Dakota. She attended Huron College. She was appointed as a Democrat by the Governor of Minnesota to the Senate vacancy caused by the death of her husband, and served from January 25, 1978 to November 7, 1978. She was not a candidate for election to the unexpired term. She is interred in Lakewood Cemetery in Minneapolis, Minnesota, next to her first husband Hubert H. Humphrey.