Diablo 4's post-credits scenes introduce potential new major villains.

Mephisto's return as a villain is teased in Diablo 4.

The post-credits teasers feature a horned demon resembling Mephisto.

Diablo, the Lord of Terror, may play a significant role in the game.

There could be an alliance between Mephisto and Diablo.

Inarius might transform into Diablo's version of Satan.

Diablo 4 presents an opportunity for iconic characters to undergo a change of heart.