Green’s Dictionary of Slang

(orig. US) a ladies’ man.

1938		Lil Hardin Armstrong ‘Harlem on Saturday Night’ 🎵 Now, all the Sugar Hillers are a bunch of killer-dillers, / I’m tryin’ to set you right.
1947		M.H. Boulware Jive and Sl.
1987		W.D. Myers Crystal 104: ‘Nerd? Me? I was a killer!’ Daniel Brown said. ‘A stone killer-diller!’.