Third wife, Sarah, is Mac Davis' ex-wife.
Used to play golf with Alice Cooper every day when Glen lived in Phoenix.
Was a touring member of The Beach Boys, filling in for an ailing Brian Wilson in 1964 and 1965. He played guitar on the group's "Pet Sounds" album, among other recordings. On tour, he played bass and sang high harmony.
Was hand-picked by actor John Wayne to play alongside him in the western film True Grit (1969), which gave Campbell a Golden Globe nomination for "Most Promising Newcomer," and had a hit with the title song which was nominated for an Academy Award. He performed it live at that year's Academy Awards Show.
Was in great demand as a session musician in the early 1960s. He was part of the famous studio musicians clique known as "The Wrecking Crew," many of whom went from session to session together as the same group.
When his career went into a decline, he developed a drug problem from which he recovered. In November 2003, however, he was arrested for drunk driving that included a charge of battery to a police officer, which was later dropped. He was sentenced to 10 days in jail and community service.
While in his early stages of Alzheimer's, he plans to release his last album before beginning his final farewell tour.