Grunworth Nivor is a minor character in the novel Pyramids, his only appearance in the Discworld series.
Grunworth is the housemaster of Viper House in the Assassins' School and teaches Traps and Pitfalls to student Assassins. He has a keen interest in edificeering so got along well with Teppic, a pupil after his own heart. He is described as being fat and jolly with a rosey face.