What notable collaborations did Billy Preston make with the Beatles?

Billy Preston recorded several albums for the Beatles’ Apple Records and added a driving organ to the song “Get Back” (1969), which was credited to “the Beatles with Billy Preston,” the only time the group shared credit with another artist. He also contributed to the albums Abbey Road (1969) and Let It Be (1970), and he was part of the band’s legendary rooftop concert during the making of the documentary film Let It Be (1970).

Source: britannica.com