Green’s Dictionary of Slang

1. (US) a Ford automobile [Henry Ford I (1863–1947), the patriarch of the automobile assembly line].

1917		Carleton B. Case Ford Smiles 3: What perversity of human nature has developed the recent propensity to ‘josh’ a wonderful machine, that has benefited the very people who laugh at their own ‘tin lizzies’ and ‘henrys’?
1927		‘J.M. Hall’ Anecdota Americana I 60: ‘Why is a Ford car called a Henry in Detroit and a Lizzie in New York?’ ‘Because by the time it gets to New York it loses its nuts.’.
1983		National Lampoon Feb. 85: On the New Jersey turnpike in a stolen ‘Henry J.’ [HDAS].
1991		R.G. Barrett Between the Devlin 143: ‘[A]ll they’ll find inside that old blue Henry is steak and kidney and crumbed brains’.

2. (drugs) heroin [initial letter; also note heroin is seen as a ‘masculine’ drug, see boy n.² (5a)].

1953		‘William Lee’ Junkie (1966) 99: All that good Henry and Charley. When you shoot Henry and Charley, you can smell it going in.
1956		H. Whittington Forgive Me, Killer (2000) 65: Nobody got me on it. I got me on it. For kicks. [...] Then it added up. Gambling. Drinking. And my friend Henry. Friend Henry really put on the finish.
1969		R.R. Lingeman Drugs from A to Z (1970).
1971		E.E. Landy Underground Dict. (1972).
2001		ONDCP Street Terms 11: Henry — Heroin.

3. see Henry VIII n.

4. see hooray (Henry) n.