
George Harrison invited Eric Clapton to play the lead guitar solo on While My Guitar Gently Weeps because he felt the Beatles would behave better in the studio with an outsider present. Clapton initially refused, saying no one played on Beatles records, but Harrison persuaded him. The resulting solo is understated, melodic, and perfectly serves the song — a model of restraint from one of rock's most capable players.
Reference:
TaskLoco™ — The Sticky Note GOAT