Frances Conroy (born March 15, 1953) is an American actress. She is most widely known for playing the matriarch Ruth O'Connor Fisher Sibley on the HBO funeral drama series Six Feet Under, which earned her a Golden Globe in 2004. Frances Conroy (born March 15, 1953) is an American actress. She is most widely known for playing the matriarch Ruth O'Connor Fisher Sibley on the HBO funeral drama series Six Feet Under, which earned her a Golden Globe in 2004.