Who is the next big bad coming to Diablo 4 after Mephisto?

From Lilith to Mephisto, the lineup of villains to vanquish in Diablo 4 has yet to disappoint. But now the eponymous Lord of Hatred has been defeated, banished to the void from which we pulled his daughter. So who will we find ourselves fighting in the next Diablo 4 expansion? Fortunately for us (and the devs), there are still plenty of big name bad guys to fight in the Diablo universe. But who will reign supreme? Let’s discuss the  contenders for Diablo 4‘s next Big Bad Evil Guy/Gal/G(t)hem.

Diablo, Lord of Terror. The titular villain, literal name of the franchise. Weirdly, we’ve seen neither hide nor hair horn of the Lord of Terror — strange, when Diablo was the final boss of the first three games. And yet nothing has shown up thus far to indicate Al’Diabolos will be the next to descend upon poor Sanctuary despite Rathma’s prophecy foretelling not just the return of grandfather Mephisto, but Ba’al and Diablo as well. After all, we did defeat of Diablo-in-Prime-Evil form in the High Heavens during Diablo 3 — but afterwards he and the other Evils were freed from the Black Soulstone thanks to one rogue angel. Diablo could be ready for a comeback

Malthael, the fallen Archangel of Wisdom turned Angel of Death. We defeated him in Pandemonium Fortress after cleaning up his forces of death (namely Reapers) after their decimation of Westmarch. We’re staving off those very same forces in D4 Season 14, thanks to a wayward cult. Are the developers telegraphing the rebirth of Malthael through the (destroyed, as of Diablo 3) Crystal Arch? Everything we know about the Crystal Arch has indicated angels are not reborn, but spawned as a new being. So it would make less sense for Malthael to return, and more for another being to have controlled his former minions.

Baal, Lord of Destruction. That’s where our third possibility comes in, because what aligns with Death more than Destruction? I think Baal is our most likely candidate, attracting the former minions of Malthael with the goal of killing all life. He literally wants to destroy everything. What better allies to attract than Reapers with which to slay humanity. Not to mention, we haven’t seen old Tor’Baalos since his absolute slaughter of the Barbarian tribes of Mount Arreat in pursuit of the Worldstone during Diablo 2: Lord of Destruction. This may be a good time to bring Baal to the forefront of the story.

For now, we await additional news — and we suspect some may show up during BlizzCon 2026. There are two Diablo 4 developer panels on the schedule, after all, and the devs (probably) can’t reveal the Season 15 theme twice! Until then, share your speculations in the comments below, and we’ll see you in Sanctuary.