Sinis was a notorious brigand, the son of Polypemon and Sylea. He was nicknamed Pityocamptes ('pine-bender') for his habit of tying his victims' limbs to pine trees that he had bent low, and then releasing the trees.

This either catapulted the victims to their deaths or rent them asunder - a hideous quartering without a previous hanging or drawing. Theseus killed him, as he often did, by applying the dastard's own devices to himself. Sinis' name means 'destroyer', 'ravager', 'robber' (sinis).