Green’s Dictionary of Slang

a human being; esp. in pej. use, e.g. queer specimen.

1836		Berks. Chron. 30 July 4/5: A squat, bow-legged figure [...] exhibiting in his whol appearance an ugly specimen of the ‘All-round-my-hat’ fraternity.
1852		C.A. Bristed Upper Ten Thousand 109: ‘There,’ said Masters, ‘is a very fair specimen of “second set”.’.
1868		‘I Want to Make the Riffle’ in Lingenfelter et al. Songs of the Amer. West (1968) 138: I look a rough old specimen, and I’ve had a rough career / Trying to make the riffle for more than twenty year.
1878		J. Hatton Cruel London III 147: ‘Fine old English gentleman, I suppose.’ ‘Yes, a good old specimen.’.
1889		K. Munroe Golden Days of ’49 272: Ain’t he a healthy specimen though?
1897		W.S. Maugham Liza of Lambeth (1966) 108: Pretty specimen she is!
1903		Bulletin (Sydney) 9 July 36/2: You look after me! [...] nice specimen you are to look after any woman.
1914		C. Holme Lonely Plough (1931) 219: He’s a queer specimen.
1926		‘Sapper’ Final Count 912: Then some bright specimen had an idea which held the field for quite a while.
1931		O. Strange Law O’ The Lariat 132: He don’t seem to have no high opinion o’ sheriffs, judgin’ by what he told the specimen they got in Hope.
1941		F. Sargeson ‘That Summer’ in Coll. Stories (1965) 156: He wasn’t a rangy specimen like me.
1950		A. Buckeridge Jennings Goes To School 29: Come here, Temple – you miserable specimen!
1960		J. Brosnan Long Season (1975) 144: As a hitter I’m a pretty tired looking specimen.
1974		R. Blount About Three Bricks Shy of a Load 56: Jeez, he’s such a specimen.
1993		T. Winton Lockie Leonard: Scumbuster (1995) 70: These specimens are two reprobates from my school.
2001		P. McCabe Emerald Germs of Ireland 364: It’s no good locking a specimen like him away in chokey.