Satan is actually a person

 Rabbeinu Bachya (Kad HaKemach, Providence 1:5) Rav Saadiya Gaon  said that Satan mentioned in the book of Iyov was actually a person who was complain about Iyov out of hatred and jealousy because of his success and good deeds. Similarly he says that the “Children of G-d mentioned there were his contemporaries who also hated him and were jealous. The reason one of them is called Satan is because he was the most famous of all of them and was their leader

Rabbeinu Bachya (Kad HaKemach, Providence 1:6) However the Ramban and the majority of comentators to Iyov say that Satan is an angel and the Children of G-d are also angels. Ramban says that our tradition is that he was created as an angel to prosecute and harm mankind. Our Sages (Bava Basra 16) have stated that Satan is the yetzer harah and the angel of death – obviously he is an angel not a person. There are many statements of our Sages which support the idea that he is an opposing and harmful angel. Our Sages also say he is the angel of Esau who is involved in fighting and wars, The demons referred to as sheidim or satyrs also are associated with Esau.