Iblees is the primary devil in Islam. He appears more often in the Qur`an as the Shaitan, a term used to refer to all of the evil spirits assisting Iblees, but which is often used to refer to just Iblees. Iblees is mentioned 11 times, and Shaitan "al-Shaitaan" is mentioned 87 times. He is chief of the spirits of evil (Shaitan).
Iblees was a Jinn, a creature made of smokeless fire by Allah سبحانه و تعالى(like humans are made of "clay"). In an outburst rooted in envy, Iblees disobeyed Allah سبحانه و تعالىand was expelled from the grace of Allah سبحانه و تعالى. He was later sent to earth along with Aadam عليه السلامand Hawwa عليه السلامafter having lured them into eating fruit from the forbidden tree, although in this role he is always referred to as ash-Shaitan.
He tempts humans through his whisper (waswas, "he whispered") of sinful ideas in their head and false suggestion (haiif). In the end, it is believed, he will be cast into Jahannam (Hell in Islam) along with those who give in to his temptation of sinful ideas and disobeyed Allah`s عليه السلامtrue message to mankind (Islam), while those who successfully try to follow a righteous path will be rewarded with the pleasures of Jannah (Paradise or Heaven in Islam).
[Iblees] said, "Do You see this one whom You have honoured above me? If You delay me until the Day of Resurrection, I will surely destroy his descendants, except for a few." Qur’an.Surah Al-Isra 17:62.
And (remember) when We said to the angel: “Prostrate yourselves before Adam عليه السلام”. And they prostrate except Iblees (Satan), he refused and was proud and was one of the disbelievers (disobedient to Allah سبحانه و تعالى). Qur’an.Surah Baqarah 2:34.
Jabir (Ra) reported: I heard Allah's Messenger ﷺas saying: The throne of Iblis is upon the ocean and he sends detachments (to different parts) in order to put people to trial and the most important figure in his eyes is one who is most notorious in sowing the seed of dissension. Sahih Muslim: 'Kitab Sifat Al-Qiyamah wa'l Janna wa'n-Nar', H: 6754
Narrated Said bin Al-Musaiyab رضي الله عنه: Abu Huraira رضي الله عنه said, "I heard Allah's Apostle saying, 'There is none born among the off-spring of Adam , but Satan touches it. A child therefore, cries loudly at the time of birth because of the touch of Satan, except Mary and her child." Then Abu Huraira رضي الله عنهrecited: "And I seek refuge with You for her and for her offspring from the outcast Satan" (Qur’an.Surah Al-Imran 3.36) Sahih Bukhari Vol 4:641