What is "dantalion"

In demonology, Dantalion (or Dantalian) is a powerful Great Duke of Hell, with thirty-six legions of demons under his command; he is the 71st of 72 spirits of Solomon.

He is depicted as a man with many appearances, all of which are those of men and women. There are also many depictions in which he is said to hold a book in one of his hands, such as the following, from the Lesser Key of Solomon:

"The Seventy-first Spirit is Dantalion. He is a Duke Great and Mighty, appearing in the Form of a Man with many Countenances, all Men's and Women's Faces; and he hath a Book in his right hand. His Office is to teach all Arts and Sciences unto any; and to declare the Secret Counsel of any one; for he knoweth the Thoughts of all Men and Women, and can change them at his Will. He can cause Love, and show the Similitude of any person, and show the same by a Vision, let them be in what part of the World they Will. He governeth 36 Legions of Spirits; and this is his Seal, which wear thou, etc."

Dantalion is mentioned in the lyrics of the song Future Times by the progressive rock group Yes on their 1978 album Tormato. "Dantalion will ride again: raging forth underland."