A Qareen [Qarin literally means constant companion] .
What is a Qareen , if you watched Hollywood movies, you might have seen the angel and devil standing on the shoulder of human, where the angel gives good advice and the devil giving out the bad advice? Well, a Qareen is a devil on the shoulder, however, it's an Arabic word used in the Quran and according to some opinion, Qareen is Satanic / Devilish.
Do not confuse Qareen with Qarinah. Qarinahis is a different entity.
Qareen is classified among the Jinn-type creatures, although usually not actually a Jinn.
Qareen can be summoned.