Unpleasant people in general. 1  a dog in the manger idiom. 2  a nasty piece of work idiom. 3  a tough/hard nut idiom. 4  a wolf in sheep's clothing idiom. 5  bad lot. 6  know-all. 7  know-it-all. 8  leech. 9  make sb's skin crawl idiom. 10  malcontent. 11  runt. 12  sadist. 13  scum. 14  scumbag. 15  sham. 16  vermin. 17  villain. 18  villain of the piece idiom. 19  viper. 20  vulture.