Benedito Moreira de Carvalho (August 10, 1910 – 1976), known as The Monster of Guaianases (Portuguese: Monstro de Guaianases), was a Brazilian serial killer and child rapist who killed eleven young girls in Greater São Paulo from 1937 to 1952. Ruled unfit to stand trial, he was imprisoned in a psychiatric hospital until his death in 1976.