pistolero

noun, plural pis·to·le·ros [pis-tl-air-ohz; Spanish pees-taw-le–raws] /ˌpɪs tlˈɛər oʊz; Spanish ˌpis tɔˈlɛ rɔs/. (esp. in Mexico and Central America)

1. a member of an armed band of roving mounted bandits.
2. a gunman or hired killer.

n.1937, from Spanish; see pistolier.