Most famous for playing the keyboard in The Doors, Manzarek joined the Army during the buildup to Vietnam. He served in Thailand and Okinawa before being kicked out. Manzarek, who had been a student at UCLA Film School before enlisting, returned to college. Only two months after graduation, Manzarek and Jim Morrison formed The Doors and became icons.
https://www.wearethemighty.com/articles/famous-military-musicians/
AND Mike Nesmith (Monkees):
Nesmith, born and raised in Dallas, Texas, dropped out of high school to join the Air Force in 1960. He spent his entire military career close to home, with basic training at Lackland Air Force Base in San Antonio and aircraft mechanic training at Sheppard Air Force Base in Wichita Falls. He spent the rest of his career stationed at Clinton-Sherman Air Force Base in Oklahoma.
https://www.military.com/off-duty/music/2021/12/13/air-force-vet-michael-nesmith-was-more-just-monkee.html
AND grunge musician Jason Everman
As a former Army Ranger and Green Beret, the guitarist for Nirvana and Mindfunk and bassist for Soundgarden served tours in Iraq and Afghanistan. He served from 1994 to 2006, earning the rank of sergeant first class.
https://coffeeordie.com/military-veteran-musicians/