Nithael

Nithael - in the cabala, an angel formerly of the order of principalities.  Barrett, The Magus, claims that Nithael is, despite his fall, still one of the 72 angels bearing the name of God Shemhamphorae.  The prevailing belief is that Nithael joined Satan during the rebellion in Heaven and that now, in Hell, he governs emperors and kings, also civil and ecclesiastical personages of the highest rank.  For Nithael's sigil, see Ambelain, La Kabbale Pratique, p.289.  (a)

Resource List - all entries are taken verbatim from the original source:

(a) "The Dictionary of Angels" by Gustav Davidson, © 1967