Spirits in the middle-east. They can be evil or good. Control other beings, or help them.
In original Middle Eastern lore, djinni occupy a position somewhere between European notions of angels and faeries and exist in both folklore and religious writings.
In most (not all) United States pop culture story universes with their fondness for hierarchies in their kitchen-sink magical realities, genies are the apex magical beings, second only to the gods themselves and more powerful than even Puck in the *Gargoyles* storyline or the *Bewitched* witches in crossover fanfic. Nearly all depictions of genies in American stories can be traced back to either the gigantic godlike genie in the 1930s *Thief of Bagdad* film starring Sabu or various film/TV versions of the *Aladdin and the Lamp* story that had been appended to *1001 Nights* and have little to do with their original depiction in Middle East myth and folklore.