http://en.wikipedia.org/wiki/Azazel
http://en.wikipedia.org/wiki/Book_of_Enoch#Description
The first section of the book depicts the interaction of the fallen angels with mankind; Sêmîazâz compels the other 199 fallen angels to take human wives to "beget us children".
And Semjâzâ, who was their leader, said unto them: 'I fear ye will not indeed agree to do this deed, and I alone shall have to pay the penalty of a great sin.' And they all answered him and said: 'Let us all swear an oath, and all bind ourselves by mutual imprecations not to abandon this plan but to do this thing.'. Then sware they all together and bound themselves by mutual imprecations upon it. And they were in all two hundred; who descended in the days of Jared on the summit of Mount Hermon, and they called it Mount Hermon, because they had sworn and bound themselves by mutual imprecations upon it.
The names of the leaders are given as "Samyaza (Shemyazaz), their leader, Araqiel, Râmêêl, Kokabiel, Tamiel, Ramiel, Dânêl, Chazaqiel, Baraqiel, Asael, Armaros, Batariel, Bezaliel, Ananiel, Zaqiel, Shamsiel, Satariel, Turiel, Yomiel, Sariel."