There's a possibility that the main villain of Diablo 4 isn't the one you think it is. The post-credits teasers have sparked theories on who we'll go up against next, and one of them is a galaxy-brained take on a baddie much, much worse than the demons you've known for decades.
Diablo isn't a particularly subtle series, but the campaign in Diablo 4 suggests that Blizzard is willing to break some rules when it comes to how the action RPG handles its villains. And given that this is the first live service Diablo, you can probably expect to see pieces of a broader story come together as new seasons and expansions are released.
Here are the current popular theories on who the four post-credits scenes depict and what that means for future seasons and expansions.
Expect full spoilers for Diablo 4's campaign and the entire series below.
Demon dad returns
You've heard him throughout Diablo 4's campaign as the mysterious bloodied wolf: Mephisto is the father of Lilith, and one of the three main villains in the series. Diablo 4's story leaves him trapped in a magical shard carried by Neyrelle at the end of the campaign. He's alive and unhappy about being cooped up in a crystal. It's a Chekhov's Lord of Hatred situation—you just know this cranky, lanky dude is coming back in full form at some point.
Three of the four post-credits teasers (the last three in the video above) feature a tall, horned demon who's giving everyone Mephisto vibes. In Diablo 2 and other miscellaneous Diablo media, Mephisto has the same long, bony physique as the figure in the teasers. And he's the only Prime Evil we've seen so far in Diablo 4. Diablo and Baal are only mentioned.
Mephisto technically helps your character, the Wanderer, throughout Diablo 4, but it should be noted that he's the shadiest Prime Evil, known for his intelligence and cunning. For all we know, he planned this. Someone should tell Neyrelle before he talks her into cracking open that stone and setting him free. Mephisto isn't a fan of humanity regardless of how much he helps you throughout the campaign. With Lilith gone, he could step in as the current demon in charge. I fully expect to 1v1 this guy at some point in Diablo 4.
The Lord of Terror tries again
Diablo 4 is the first in the quadrilogy to not feature Diablo, the Lord of Terror, as a boss. He's barely even mentioned in the game, despite having been released back into the wild by Malthael in Diablo 3: Reaper of Souls. Surely he's not pleased with the way the whole one, true Prime Evil plan played out in 3's campaign.
While I'm not entirely convinced any of the post-credits teasers are him considering how similar they look to Mephisto, it's a possibility worth considering. Diablo, like his brothers, isnt't into the whole humanity thing and would prefer if humans stopped interfering with the Eternal Conflict between angels and demons.
Sanctuary, the domain of humanity, is ripe for meddling at the moment. Food and water are in short supply, demons are everywhere, and people are resorting to some pretty nasty things to survive. It's possible that having us kill Lilith was all part of Mephisto's plan and, for all we know, he could be working with his brother. The Prime brothers have had disagreements in the past, but Diablo 4 establishes that these are unprecedented times for everyone, the demons in particular. With no word from the High Heavens and what seems to be a lull in the Eternal Conflict, Diablo could be about to make the first move he's made in a long time.
Inarius' goth era
Diablo 4's most pathetic character, Inarius, gets his wings torn off and a spear to the heart just before the game ends. Reddit user GenuisInDisguise thinks the fourth teaser is evidence of the angel coming back as Lucifer, the one figure in Christianity who Diablo hasn't borrowed yet. Inarius helped create humans and was exiled from Heaven—the same fate as Lucifer. He's also prideful to a fault in Diablo 4, which was Lucifer's major sin. Inarius might be poised to become Diablo's version of Satan.
The last shot of Inarius sees him essentially melting into the floors of Hell and the teaser shows a demonic skull that seems to be rising upward. Inarius might return as a proper leader for the demons and it could be yet another piece of a larger plan that includes Diablo and Mephisto.
Inarius knows a lot about the High Heavens, and the last thing the angels would want is the guy they kicked out to come back wearing the other team's jersey. Although I doubt it will be as simple as Inarius stepping in as Lilith's replacement as a villain, it would work thematically. Lilith was also turning on her own kind with her plans to use humans to end the Eternal Conflict. What if Inarius seeks to end it too?
Diablo 4 has technically just started its years-long journey as a live service game, but the world seems to be right on the cusp of its most iconic characters having a change of heart. I'm skeptical of how the post-credits scenes frame these old demons as threatening when much of the campaign works to give them more depth than a typical Diablo villain. They're still evil, sure, but they could be useful. And, who knows, maybe we'll finally get the chance to shake hands with Diablo and thank him for all the loot he's given us over the years.