Green’s Dictionary of Slang

(orig. US) a short person or child.

1876		J. Miller First Fam’lies in the Sierras 105: Here’s to it! Here’s to the Little Half-a-pint [...] they did not know the baby’s name.
1926		Maines & Grant Wise-crack Dict.
1929		W.R. Burnett Little Caesar (1932) 106: The half-pint’s a good boy.
1936		K. Mackenzie Living Rough 193: Why you little, sawed-off, hammered-down half-pint.
1941		B. Schulberg What Makes Sammy Run? (1992) 14: I was letting a twelve-buck-a-week halfpint bulldoze me.
1947		N. Algren Neon Wilderness (1986) 20: The next was a half-pint with his cap on backward.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 190: Dumpy, flea, half-pint, imp.
1959		(con. WWII) B. Cochrell Barren Beaches of Hell 225: I said knock it off, half-pint.
1960		E. De Roo Big Rumble 150: Who you spittin’ at, half-pint?
1960		E. North Nobody Stops Me 63: This dolled-up half-pint of a kid talking to me like that!
1975		Xenia Dly Gaz. (OH) 29 Sept. 2/5: ‘She’s just a half-pint’.
1986		S. King It (1987) 548: Never called any of them by name, Eddie remembered. It was always hey Red, [...] hey Half-Pint.
1997		Da Bomb Summer Supplement 7: Half pint (n.) A small guy.