Green’s Dictionary of Slang

hero (of the underworld) n.

(drugs) heroin.

1953		Anslinger & Tompkins Traffic In Narcotics 310: hero. Heroin.
1971		E.E. Landy Underground Dict. (1972).
2001		ONDCP Street Terms 11: Hero — Heroin; Hero of the underworld — Heroin. Heroina (Spanish) — Heroin.