Saint Dane is the main antagonist from the Pendragon series of books.
He appears to be a maniac and a genius at the same time, and appears in all 10 books, along with Bobby Pendragon, Mark Dimond, and Courtney Chetwynde. He wants to break down Halla so he can rebuild it in his own design.
He isn't from a territory but from Solora, the birthplace of all Halla. Saint Dane has the ability to transform into any person, animal, and even "smoke" on certain occasions, making it harder for Bobby and co. to realize who he is and what he's doing.
He is known for his icy, blue eyes. He has been involved in the deaths of many characters, including Osa, Uncle Press, Spader's father, Seegen, Loor (temporary), Remudi (the traveler from Ibara), and more. Saint Dane is cruelty personified. He was also a boy named Andy Mitchell, a bully, that has been tormenting Mark Dimond for years since kindergarten.
Saint Dane did that so he can set up Mark, by then pretending to be his friend and then got him to First Earth to create a company known as the Dimond Alpha Digital Organization, which is spelled as DADO. He usually makes a complex plan to overthrow a territory before actually doing it. He doesn't fear death or suffering, because he can resurrect himself, but enjoys other people suffering.
He often tricks Bobby into causing the destruction of a territory (like in the 3rd Pendragon book, where he almost convinces Bobby to stop the Hindenburg from crashing, which would result in the Nazis victory of World War 2.) without actually personally affecting the territory too much. He also has the power to manipulate people with his mind. He cannot be killed by ordinary means. Press tells Bobby that Saint Dane can only die when he truly believes he has won (the destruction of Halla), which occurs in Raven Rise, the 9th Pendragon book.