ShortList collects their 50 favorite literary insults. From Salinger's The Catcher in the Rye:
I told him he didn’t even care if a girl kept all her kings in the back row or not, and the reason he didn’t care was because he was a goddam stupid moron. He hated it when you called him a moron. All morons hate it when you call them a moron.
From Dostoyevsky's Crime and Punishment:
He was one of the numerous and varied legion of dullards, of half-animated abortions, conceited, half-educated coxcombs, who attach themselves to the idea most in fashion only to vulgarize it and who caricature every cause they serve, however sincerely.
And from Shakespeare's As You Like It:
“I desire that we be better strangers."