Donald "Buck Dharma" Roeser (born November 12, 1947, in Long Island, New York) is an American guitarist and songwriter, best known for being a member of Blue Oyster Cult since the group's formation in 1967. He wrote and performed on many of the band's best-known hits, including "(Don't Fear) The Reaper" and "Burnin' For You" (originally intended for one of Roeser's solo albums.)

The nickname came from an idea from the band's manager, Sandy Pearlman, who envisioned each member of the band having an unusual stage name; Roeser was the only one who took to the idea, and his was the only name that stuck.

User-contributed text is available under the Creative Commons By-SA License and may also be available under the GNU FDL.