There was at least one album’s worth of music by George Michael where he refused to, or wasn’t allowed to, appear in most of the music videos, due to some kind of contractual dispute with Sony Music.
I heard somewhere that when they decided to make a video for **Abracadabra **by Steve Miller he was touring in some other country so they made the video without him in it.
Amy Winehouse was either in rehab or “otherwise unavailable” for her Valerie video, so it’s done as lip-synced karaoke.
I don’t believe Elton John appears in the videos either This Train Don’t Stop Here Anymore or I Want Love; in the former he’s played by Justin Timberlake as his younger self, while the latter is lip-synced by Robert Downey Jr.
Madonna and MTV ran a contest in 1986 inviting people to make a video for her song “True Blue”. Obviously she did not perform in the entries that were submitted, including the winning one.