A couple of years ago when I was developing a game concept for a big brand, I came up with the idea of a satana ex machina. While a deus ex machina provides a solution to resolve a conflict, the satana ex machina would provide the initial problem of a story.
Of course, a deus ex machina is a weak narrative element and its counterpart probably wouldn’t be any better since these figures are completely removed from the story and don’t have any stakes in resolving or creating conflict. Still in all, I found the idea of an infernal imp creating havoc for the protagonist intriguing. And I think that a satana can be more palatable than a deus since the audience wants to see the protagonist solve a conflict, but the source of the conflict isn’t as important to understand.
But a villain whose motivations is understood is always meatier.