Written and first recorded (as a demo) by Paul McCartney (1968).
Hit version by Mary Hopkin (US #13/UK #2/CAN #14/NETH #1 1969).
From the wiki: “‘Goodbye’ is a song written by Paul McCartney (but credited to Lennon–McCartney) and performed by Mary Hopkin. The song was conceived as a follow-up to the success of Hopkin’s first single, produced by McCartney, titled ‘Those Were the Days‘, highlighted on her debut album Postcard, one of the first records issued by the newly founded Apple Records.