The Igors are a species native to Discworld. They live in Uberwald and are humanoid. Everyone of them is called Igor (or Igorina, if female). The Igors are not undead, but they are related to the undead. Most time Igors are servants of Vampires or mad doctors. Strangely Earth's Vampires nerver have Igors as servants.
Igors love to transplant human organs. Some of them are transplanting the organs of their dead relatives to themselves. So if someone says: "He has his grandfathers hands", this might be literally true.