Ruth was the daughter of Herman Lissauer and Nina (Weiss) Rudolf. who divorced when she was six, her father going on to become the Head of Research at Warner Bros. Initially a piano prodigy, Ruth’s interest in music developed from exposure to her mother's professional chorus singing work
At age 16 or 17, working as secretary at Twentieth Century Fox, Olay undertook singing lessons with vocal coach Florence Russell (Dorothy Dandridge). While at work, she met one of Duke Ellington's vocalists, Ivie Anderson. Together they attended the venue where Ellington was playing and Olay was persuaded to sing. In 1942, at her mother's re-marriage party she sang and impressed a guest, the wife of songwriter Irving Gordon (Throw Mama From the Train, Unforgettable). Gordon in turn introduced Olay to jazz musician Benny Carter who became her musical mentor.
In the summer of 1951, Benny Carter's band from Los Angeles with Gerald Wiggins, Bill Douglas and Ulysses Livingston was booked into Club Royal in San Diego. People knew that Benny had a white girl singer named Sue Lowrey (Ruth Olay), who would be unwelcome. She and Benny decided to beat the system. Sue/Ruth acquired a fast sun-tan and became "Singer Rachel Davis" for four weeks. To help keep her secret—and her gig—the band joined her on the beach for two hours of sunshine and volleyball every day in July so she wouldn't lose her identity.
She later performed with Jerry Fielding in Los Angeles and Beverly Hills clubs, all the while holding down a secretarial day job at Twentieth Century Limited, including work for celebrated screenwriter Preston Sturges. At the Cabaret Concert Theatre where she both waitressed and sang, she came to the attention of Bill Hitchcock of Zephyr Records. Olay's first LP on Zephyr in 1956 was promoted as coming from "the blues shouting tradition", "pop style" and "swinging interpretation".
While gigging at the Little Club, Olay was approached by Bill Burton, who managed, among others, Jimmy Dorsey and Dick Haymes, and soon got her big break when Burton booked her an emergency gig at the Avant Garde Club in replacement of Billie Holiday, who had fallen ill. This developed into a headline run, along with Shelley Berman, Matt Dennis Trio and Lenny Bruce. A regular at the club was arranger Peter Ruggolo, who A&R'ed for Mercury Records.
Her first LP on Mercury OLAY! in 1958 was followed by a guest vocalist spot on Jack Paar's Tonight Show. She became the "Singing Sensation of the Jack Paar Show" during Paar's stint, and also appeared later on Johnny Carson's watch, the latter time backed by Duke Ellington. Subsequent appearances included Jerry Fielding's TV show, and with Merv Griffin, Jackie Gleason and Steve Allen. In 1961, Olay found time to play the role of Julie in Lewis & Youngs' production of Showboat.
For the second LP Easy Living on Mercury in 1959, Olay was set up with Jerry Fielding whose credits included arranging with big bands such as those of Kay Kyser, Claude Thornhill, Jimmie Lunceford, Tommy Dorsey, Charlie Barnet, and Les Brown. LP's followed on diverse labels after Olay's departure from Mercury and she continued nightclub appearances and TV shows well into the 1960s (e.g.: Sue Rainey on KTLA June 11, 1965).
From 1972 to 1976 she spent some time performing in Europe where the popularity of American jazz persisted , but whist in Copenhagen she had to press jeans in a laundry to pay the rent between gigs. After returning to the USA, she joined up with the Red Mitchell Trio in 1982 for the album "Ruth Olay Sings Jazz Today." In 1985 she released “Watch What Happens” on Laurel Records. She was still performing in 1987 with a venue at the the Vine St. Bar & Grill in Hollywood then gradually phased into retirement and withdrew from singing altogether.
In an interview with Bill Reed in 2000 she said “The voice gave out because I didn't use it. And it's very true that if you don't use it you lose it. I didn't vocalize and I just got very lazy and was not motivated to continue with the anxiety of working. I just didn't want to go through that anymore. I just quit singing. Beautifully so, thank God.”
In her later years she turned her attention more in the direction of social activism on various commissions for aging, the homeless, etc.. Also if you looked closely you could have spotted her in the crowd outside of Los Angeles' Dorothy Chandler, in 1999, protesting Elia Kazan's Lifetime Achievement Oscar.
Ruth was married three times, firstly to Lionel Olay from 1947–1949, and whose name she adopted as her stage name. They had a daughter, Amy, born in 1949, and there is a son from a subsequent marriage. Her second divorce was in 1961. In 1963 she married her manager Lee Magid (Earl Grant, Lou Rawls, Della Reese), and together they had a son, Adam. (Info mainly edited from Wikipedia)