The Diablo games all feature players banding together to fight back hordes of demons and undead from Hell that are trying to invade the fantasy world of Sanctuary. Each entry in the series expands on its world and lore as players choose from a selection of different warriors that all bear their own abilities and proficiencies. One element that has to change in a Diablo title, however, is the series' antagonist, Diablo himself, also known as Lord of Terror, The Dark Lord, or The Prime Evil.
Throughout the games, Diablo's plot to claim the mortal realm for Hell changes and morphs as he is repeatedly defeated or sidelined by players. However, he has left his mark on the games industry and is one of the most widely recognized antagonists in games. For players who are eager to jump into Diablo 2: Resurrected for the first time, or players who want to get into Diablo 4 in the future, Diablo's plans and nature may seem a bit confusing as a consequence of how deep and thorough the lore of the series is. For those players, or any who just want a quick refresher on the industry's favorite devil, here is the lore behind the Lord of Terror.
The Birth of Diablo
Diablo is one of the game's seven Great Evils, which are the most powerful demon lords in all of Hell. The demons are split into three Prime Evils and four Lesser Evils and were born via the death of the Progenitor dragon named Tathamet. Tathamet was born from Anu, the first being of creation, who cast all the evil out of himself that formed the dragon. The two beings eventually fought one another until they both died, leading to the creation of Heaven and Hell as well as Angels and Demons. Tathamet had seven heads, which each became one of the Great Evils upon his death and lived in Hell, which was created with his dead body. This origin event is the foundation for all of the lore in Diablo.
One of Tathamet's heads bore Diablo the youngest of the three Prime Evils. As the youngest, Diablo is widely regarded as the most dangerous of the Great Evils for how patient and cunning he is by nature. He played an integral role in the Eternal Conflict that is an endless war between the armies of Heaven and Hell. Throughout the war, the denizens of Hell frequently came close to breaking through the gates of Heaven, although they were defeated by Heaven every time after fighting amongst themselves over what spoils of the war would go to whom. This led to Diablo and other Prime Evils such as Mephisto arguing and battling with one another throughout the Diablo series.
Diablo's Battles Over Sanctuary
Eventually, Diablo became aware of the world of Sanctuary, where humans had taken root as a new race with the influences of both Heaven and Hell within them. Diablo informed the other Prime Evils of the new realm, and they began a campaign to influence the humans to do their bidding before the rogue angel Inarius noticed and began working to counter their efforts. However, the Prime Evils had kept Sanctuary's existence a secret from the Lesser Evils, which led to the Lesser Evils eventually banishing all of Diablo's Prime Evils from Hell into Sanctuary in what was known as the Dark Exile.
While the Prime Evils enjoyed some years traveling throughout Sanctuary and forcing humans to do their bidding, they were eventually stopped by Diablo's Archangels who entrapped Diablo within a soulstone and buried him beneath a small monastery to keep others from freeing him. It took 200 years for Diablo to free himself from the soulstone, but he eventually did by possession of King Leoric. Diablo was eventually defeated again, along with the six other Great Evils, but by manipulating the human known as Leah, he absorbed the essence of his dead brethren and was reborn in the mortal form of his daughter Leah. This made Diablo a new reincarnation of Tathamet, and he became the new sole Prime Evil.
Diablo's Attack on Heaven
It was then that Diablo amassed all the forces of Hell under his command and led them in an assault on the gates of Heaven. His attack was victorious, and Diablo's forces were able to force open the gates and enter the Silver City for the very first time in history. Diablo tried to kill the Heavenly Host to seal his victory, but she was saved at the last second, and Diablo was forced to battle a group of powerful Nephalem warriors, the powerful race of humans that make up Diablo's playable characters. Despite becoming the Prime Evil, and even teleporting them all to his own Realm of Terror, Diablo was eventually defeated, and his soul was returned to the black soulstone that had previously held the essence of him and all the Greater Evils.
Then, in Diablo 3's Reaper of Souls expansion, the angle of death Malthael took the black soulstone in an attempt to weaponize it to remove all demonic presence from Sanctuary. However, this would eradicate all of humanity as well, and the same group of Nephalem that defeated Diablo defeated Malthael as well. During the battle, Malthael absorbed the spirits of the Greater Evils from the black soulstone to become more powerful, but upon his death, Diablo was able to leave him while maintaining the incorporated spirits of the six other Greater Evils. However, the six other spirits were eventually able to separate themselves from him. This leaves Diablo and the other Greater Evils in interesting positions that could see them returning in some form in Diablo 4 whether it be as bosses or some other way.
It will be very interesting to see where the storyline of Diablo goes from here both in Diablo Immortal and Diablo 4. Beings in the Diablo universe just keep getting more powerful, and there are many great ways that the story could be developed moving forward. While fans have Diablo 2: Resurrected to look forward to releasing soon, hopefully, they will get some more news about what to expect from Diablo 4 sometime soon.
Diablo 4 is currently in development.