Harley Francis Flanagan (born March 8, 1967) is an American musician, known for being the bassist and vocalist of the hardcore punk band the Cro-Mags. Flanagan began his musical career at age 11 in 1978, drumming for the New York punk band the Stimulators alongside his aunt Denise Mercedes. By the early 1980s, he was a prominent figure in the developing New York hardcore, helping to found the Cro-Mags in 1981 and Murphy's Law in 1982. Although he is technically not a constant member of Cro-Mags, having left and rejoined the band on a few occasions, Flanagan is the only member to appear on all of their studio albums.

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