Written and originally recorded by The Bee Gees (1977).
Hit version by Yvonne Elliman (US #1/UK #4/CAN #1 1977).
From the wiki: “According to Maurice Gibb, this track was the first song they recorded while producing the other songs for the film Saturday Night Fever. ‘If I Can’t Have You’ was originally intended to be sung for the film soundtrack by The Bee Gees while Elliman’s contribution would be another ballad written by the Gibb brothers, ‘How Deep Is Your Love’.
“The Bee Gees produced their own version of ‘If I Can’t Have You’ for the film. However, RSO Records chairman and Bee Gees manager Robert Stigwood, who was executive-producing the Saturday Night Fever album, dictated that the Bee Gees themselves record ‘How Deep Is Your Love’ with Elliman being given a shot at the disco-style ‘If I Can’t Have You’.
“The first single off the soundtrack not performed by the Bee Gees, ‘If I Can’t Have You’ would become the fourth #1 hit from the film, reaching the top spot on the Hot 100 in Billboard dated May 13, 1978, ending an eight-week #1 tenure by ‘Night Fever’. ‘If I Can’t Have You’ was also the fourth consecutive US #1 to be co-written by Barry Gibb.”
Yvonne Elliman, “If I Can’t Have You” (1977):