Green’s Dictionary of Slang

1. a large, muscular person; thus as adj., muscular.

1890		Dead Bird (Sydney) 22 Feb. 3/3: He [...] a true English bull terrier, with a nose like a greyhound and jaws like a steel trap [...] He's a real hench dog, and fit to show in any land.
2003		BlazinParadise ‘Blazing Squad Language’ 🌐 Hench – A large well built person.
2005		Observer Rev. 14 Aug. 7/3: Hench or blench adj. – muscular: ‘Did you see how many hench guys were with him.’.
2008		A. Wheatle Dirty South 48: What advice would you give to a hench-looking young brother today, Gran?
2011		G. Knight Hood Rat 105: His snake-eyes Avirex T-shirt shows his henched core, his bull neck.
2017		theculturetrip.com ‘Guide to London Slang 10 Jan. 🌐 Hench – muscular sexy bloke you find on the tube and want to have sex with.
2018		Loski ‘Cool Kid’ 🎵 And fuck gym, I make a hench boy run from off this .15.

2. a friend.

2004

Observer 22 Feb. 7: Wigger-speak. Hench – mate.