Richard Dickie, 69, from Kirkcaldy, and Alexander Kennedy, 33, from Methil, died at the scene after the Ford Focus Mr Kennedy was driving was in collision with a Hyundai i30.
The 43-year-old Fife man driving the Hyundai was taken to Ninewells Hospital in Dundee after the crash on the A92 between Ladybank and Freuchie, which happened shortly before 6am on Wednesday.
The injured man is in a serious condition in hospital.
In a statement released through police, the family of Mr Dickie, who was a passenger in the Focus, said: "The whole family is deeply saddened by this tragedy. The loss of Richard will leave a huge hole in all of our lives."