Sectarian teachings include an entity named Dajjal. It is similar to Devil, and may really be a demonized enemy, that may originally have been correct.
The word Dajjal seems to imply that he does not like moonworship for instance, but is a monotheist (hanif in arabic).
Devil is really the same.
It is not part of kuranic or original monotheism, where Elf (Iblis Ash Shaytan in right-to-left arabic script) is the enemy. (The idolater).