Headmaster Kaien Cross is Yuki Cross's adoptive father, who also took Zero into his home for several years. Headmaster Cross dreams of peace between humans and vampires, and established the Night Class to promote understanding between the two races. Cross is shown to have a habit of provoking Zero and is eccentric in some ways, but he has a serious side as well.
The headmaster is revealed to have several secrets, including that he was a former vampire hunter. He knew both of Kaname's parents, who founded the Cross Academy peace treaty before their deaths, and feels indebted to them, in particular Juri Kuran, who had spared his life sixteen years ago after he had attempted to take away her life, not knowing then that she was pregnant with Yuuki.
During the defense of Cross Academy, Cross stands against the hunters from the Hunters Association, refusing to kill any vampires and intending only to protect the Night Class as they defend the Day Class, and asserts that he has no intention of allowing the hunters to take Yuuki. His vampire hunter weapon appears to be some sort of sword, which he uses to kill the President of the Hunters Association who had turned corrupt from drinking Rido Kuran's blood.