GNU, or Wildebeest. Its a type of antelope. Which is in the Bovidae family. It also includes Goats, Sheep, Cattle, Buffalo and Bison. Big girls with horns. Googling Gnu Monster Girl, the name Catoblepas comes up. Wikipedia says
It is said to resemble a cape buffalo, with its head always pointing downwards due to its great weight. Its stare or breath could either turn people into stone, or kill them. The catoblepas is often thought to be based on real-life encounters with wildebeest, such that some dictionaries say that the word is synonymous with "gnu".