“Hopelessly Devoted to You” was recorded by English-born Australian singer Olivia Newton-John for Grease: The Original Soundtrack from the Motion Picture (1978).
It was written and produced by John Farrar and originally performed by Newton-John in the film version of the musical Grease (1978). The song was released in Australia in August 1978 and peaked at number 2.
It reached number three on the US Billboard Hot 100 and number seven on the Adult Contemporary chart. Wiki