Azazel (עזאזל) was the leader of the fallen angels, of whom we read in the book of Enoch. Its name can also be found in the Torah, namely the Feast of Yom Kippur (Leviticus 16:8).
Azazel is mentioned in Leviticus, and many people falsely identify him to be Satan. The book of Enoch will be to our help for our understanding...