Demon

"Oh no! We have a problem! Demons! Well, I hate demons! IT'S TOO SCARY!!! Oh, that portal made them go to our world! I guess this is the end of the world as we know it! Literally!!"

--Su Ji-Hoon, The Demonic Portal

A demon (from Koine Greek δαιμόνιον daimónion) is a supernatural and often malevolent being prevalent in religion, occultism, literature, fiction, mythology and folklore.