Obviously eternal damnation sounds like an awful punishment, but thanks to the demons of Hell, you won't endure it alone. You see, the only reason hell ever lay empty was so God could fill it with the devil's demons, who made their bed in fire and brimstone once they sided with Lucifer. Capable of temptation, destruction, and possession, Hell creatures use all manner of evil to bring about the fall of man and consume his soul. While definitely nefarious in nature, these monsters simply play the role they were born to play.
Should you lead a life of lechery, sin, and unpaid taxes, you may end up as a cameo in Dante's literal Inferno, and the demons who live in Hell would be your cast. Finding yourself in the company of these terrifying demons would be, well, Hellish for sure. But then again, that's why you're there. So that you don't go into your next life rudely asking who everyone is, here's a list of entities you may share some space with Hell.
Legion, The Demon Who Is Many
Moloch, The Demon Who Demands Dead Children
Amon, The Demon With A Bird's Head And Wolf's Teeth
Adramelech, Hell Has To Have An Administrator