Dr. in what? Degree: what a passion. Of course, on top of the list here’s Dr. Bob Dylan, a recent Nobel Prize for Literature and Keith Richards. Keith called himself for a Honoris Causae Nobel Prize for for Chemistry, Heroic poisons and other unidentified substances. 
The Iron Maiden singer has a double degree.
Bruce Dickinson, frontman of Iron Maiden who holds a degree in History at London's "Quenn Mary University", after which he repeated, taking also the one in Literature.
In the resume of Tom Morello - guitarist of Rage Against The Machine and Audioslave - there is a graduate degree in Political Science at Harvard University. Sting before the Police, taught English literature, the subject for which he had obtained the degree of enrollment
Brian May and the PhD in Astrophysics
Brian May, Queen's historical guitarist, attended the Imperial College - a prestigious London university - by enrolling at the faculty of Physics and Mathematics. After graduating (in Physics), May after 30 years spent on stage playng guitars and doing Rock things, at age of 60 he earned his PhD in Astrophysics. Roger Taylor, another founder of the Queen, before being a drummer got graduated in Biology, while John Deacon, bassist of the band, has a bachelor's degree in Electronics.
Radiohead: a band of dangerous graduates
4/5 of the group possess a university degree. Thom Yorke, voice and leader has a degree in English, guitarist Ed O'Brien graduated in Economics. Drummer Phil Selway has a university degree in English and History. Bassist Colin Greenwood i graduated in English Literature.
1.Dexter Holland (singer / guitarist OFFSPRING) - Graduated in Molecular Biology at the University of South California.
2 Freddie Mercury - the Queen Frontman was Graduated Designer at London's West Thames College.
3 .James Lilja (Founder of Offspring) - A gynecology and oncology physician at the University of California.
4.Lou Reed - Graduated in English at Syracuse University.
5.David Farrell (bassist Linkin park) - graduated at UCLA in Los Angeles in Mathematics.
6.Graffin - Bad Religion punk group founder - double degree in geology and anthropology at Los Angeles Doyle.
7.Jim Morrison - Doors' voice was a Los Angeles graduate degree in theater arts and directing.
