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‘, which was highlighted on her debut album Postcard, one of the first records issued by the newly founded Apple Records.
“In later years, McCartney had little recollection of creating the song, which was written in a great hurry to capitalize on Hopkin’s popularity, but McCartney did recall being told by a boat skipper from the Orkney Islands that it was the man’s favorite song, which seemed appropriate to McCartney since, ‘if you think of it from a sailor’s point of view, it’s very much a leaving-the-port song.’
“For the Hopkin recording, Mary sang and performed acoustic guitar, while McCartney played bass guitar, an acoustic guitar introduction and solo, along with lap-slapping percussion and drums. Backing vocals, horns and strings were overdubbed.
“Hopkin’s ‘Goodbye’, like it’s predecessor, would have also been a #1 single in the U.K. but was held out of the top spot for two weeks by another of Paul McCartney’s songs – The Beatles recording of ‘Get Back,’ which held firm to the #1 spot during the entire month of May 1969. In the U.S. Billboard Hot 100, ‘Goodbye’ peaked at #13.”
Mary Hopkin, “Goodbye” (1969):