Who wrote the title song for the movie "Grease"?

"Grease" is a song written by Barry Gibb and performed by Frankie Valli. "Grease" is the title song for the 1978 musical motion picture "Grease," which was based on the 1971 stage play of the same name. The song was released as a single by Valli in May 1978 and sold over seven million copies worldwide and was featured twice on the film's soundtrack: as the first track and reprised as the final track.

"Grease" was written specifically for the 1978 musical motion picture; it had not originated from the stage production. The song was recorded separately from, and later than, the rest of the film's songs. Shortly after the filming of the 1978 musical film Sgt. Pepper's Lonely Hearts Club Band, Gibb invited castmate Peter Frampton to play guitar on the Grease session. Gibb himself provided backing vocals. Frankie Valli was approached to sing due to his similar vocal range to Barry and his status as a popular singer from the pre-British Invasion era that "Grease" represented;

Sir Barry Alan Crompton Gibb (born 1 September 1946) is a British musician, singer-songwriter, and record producer who rose to worldwide fame as a member of the Bee Gees, one of the most commercially successful groups in the history of popular music. With his younger brothers, fraternal twins Robin and Maurice Gibb, he formed a songwriting partnership beginning in 1955. He has lived in Britain, Australia, and the United States, holding dual UK–US citizenship, the latter since 2009.