Doctor Dillamond was a Goat who has the ability to speak and interact with humans. He was a professor at Shiz University. Because he was one of the only Animal professor at Shiz ("Animals" starting with a capital letter, like "Goat", are sentient beings), he is subjected to discrimination from his students and colleagues. However, Elphaba Thropp takes a liking to him. Doctor Dillamond's death causes the character Galinda to change her name to simply "Glinda," because he could not pronounce the first syllable.
In Maguire's novel, Doctor Dillamond is a Life Science teacher at Crage Hall at Shiz University (the school where Elphaba and Galinda/Glinda attend). He was once widely revered for his knowledge and experience, but at the time of the novel, the Wizard is putting forth a series of laws that restrict the rights of Animals, and these have greatly diminished the Doctor's influence. Doctor Dillamond is assisted by Elphaba Thropp and a Munchkin named Boq in researching and conducting some controversial experiments to discover the biological differences between humans, animals and sentient Animals, with the hope of proving that, since humans and Animals are the same, the Wizard's Banns have no scientific basis. Eventually, another character, Ama Clutch finds him dead in his office, his throat having been slit. Ama Clutch later claims that the Goat was murdered by Grommetik, the mechanical servant of headmistress Madame Morrible. However, this statement is never conclusively proven. Morrible claims that Dillamond fell on a broken magnifying lens, and that Grommetik, finding him lying on the ground, had merely been checking for a pulse when Ama Clutch arrived. Elphaba remains certain that Dillamond was murdered, and continues his experiments later in life. His experiments, in fact, are actually the reason that she goes to see the Wizard in the first place.