A knave is a trickster, someone who is amoral and subject to crafty practices.
Works that have knaves:
“A Satire Against Reason & Mankind” by John Wilmot, the Second Earl of Rochestor. Line 160, “men must be knaves, tis in their own defense,” it is human nature to resort to trickery to achieve one’s goals. Because everything is driven by “base fear,” men are inherently cowards and knaves.
“The Country Wife” by William Wycherley. Horner is a classic knave because he is solely focused with sleeping as many women as possible, he is amoral and doesn’t care about social conventions. He also manages to deceive Sir Jasper and Pinchwife, and successfully cuckold without them knowing it, thus showing his cleverness.