Green’s Dictionary of Slang

1. one who has a high opinion of his own powers, usu. physical.

1908		H. Lawson ‘The Song of the Back to Front’ in Roderick (1967–9) II 240: The hard man’s ‘soft’ when the crisis comes, though the whole of his life be marred.
1919		Transcript Foster Inquiry in L.R. Murphy Perverts by Official Order (1989) 11: ‘Speedy,’ had a reputation as a ‘hard man’.
1952		J. Jones From Here to Eternity (1998) 150: I’m a hard man, Angelo. Don’t mess with me. I’ll pull you apart.
1964		R.D. Abrahams Deep Down in the Jungle 70: His expression of his ego is in his physical prowess. He is the ‘hard man,’ who, because of his strength [...] is ruler through his powers and anything which threatens his domain threatens his ego and must be removed.
1984		‘Derek Raymond’ He Died with His Eyes Open 54: E thinks e’s a ard man.
1991		S. Connaughton Run of the Country n.p.: ‘Ah, the hard men,’ he called jovially to them. ‘How’s the liatroidie?’ ‘Oh, dangling nicely,’ Prunty replied with a grin [BS].
2000		Guardian Guide 5–11 Feb. 8: Most hardmen of rap are still ambivalent about being openly outed as Christians.

2. a thug, a professionally violent person.

1931		E. Dalton When the Daltons Rode in Hamilton (1952) 102: I have met hundreds of bad men, hard men, shooting men.
1948		P. Kavanagh Tarry Flynn (1965) 144: And there was blood on the stones to prove it. ‘The hard man, the hard man.’.
1966		P. Boyle At Night All Cats Are Grey 256: You’re a hard man all right, Jim. Ye made a proper butcher’s shop of him.
1972		D. Pendleton Boston Blitz (1974) 87: He could pass as a Figarone hardman.
1979		F. Norman Too Many Crooks Spoil the Caper 105: Yuh gettin’ yuhself a bigger reputation as a ’ard man than I ever did even in me ’eyday.
1983		W. Trevor Fools of Fortune 117: ‘The hard man,’ Ring greeted My Byrne [...] Mr Byrne, a dour man, once a champion wrestler, did not reply.
1993		I. Welsh Trainspotting 20: Ah am but a pawn in a game called ‘The Marketing of Mike Forrester As A Hard Man’.
2005		B. Hare Urban Grimshaw 132: Come on then, Sketter. Come and stab me if you’re a fucking hard man.
2015		L. McInerney Glorious Heresies 41: You don’t go around telling wrought-iron hard men that you know who they’ve been offing.
2018		G. Gilmore Class Act [ebook] ‘You and your hard-man friend’.

3. (Irish) a term of affection.

1969

P. Boyle All Looks Yellow to the Jaundiced Eye 115: Well, if it isn’t the hard man himself!