Red Goddess i believe deserves to become one of the Pure-Evil villains.
Who is she?
The Red Goddess is the main evil-demonic villain from the horror-disgusting video game known as Agony. She is the head-ruler of Hell. She commands and leads all the demonic-creatures in Hell. Everything what the demons do in order to torture the humans in the hell is commanded by the Goddess. Her main goal is to become the leader of Heaven. She wants to defeat God and just takes his role over. It's also notable that she loves to take God's creations and just create pleasure for herself when the creations are suffering.
She ended up teaming up with Nimrod. The two had the same goal of wanting to own Heaven. The Redd Goddess and Nimrod together worked on taking Heaven. But all of that changed when Nimrod's slave gave Nimrod a poison. When Nimrod took the poison, he started seeing everyone as evil and didn't listen to the Red Goddess. She became very upset instantly pushing Nimrod into hell for disrespecting her... After that, Nimrod wakes up in Hell, around various demonic-disgusting creatures which are wanting to punish and kill Nimrod.
She is very seductive and hungry for power. She is in love of the idea of others suffering in any-way, but mainly in a sexual way. She is also obsessed with Nimrod, to the point of feeling so much pleasure when Nimrod is suffering in Hell. Even though Nimrod betrayed her, she still wants to keep dominating him and seducing him into becoming a total-slave to her. She clearly doesn't have any emotions towards her actions. She just would want to spread suffering everywhere. But her main goal as noted is to make everyone in Heaven suffer in the most messed up ways.
MORAL EVENT HORIZON
It seems like she is delusional over Nimrod. She is in love with him, but at the same time, she would love to make him suffer the most over everyone in Hell. While she is straight when it comes to expanded power. She is permanently hungry for new demonic-horrifying power in order to dominate as much as she can.
NO REDEEMING QUALITIES
She's literally the leader of Hell. She has no remorse for any of her actions. She just wants to keep expanding the suffering of everyone. More alive-beings suffering, she's getting pleasured more and more...
She literally wants everyone to suffer in pain, she leads Hell, she is trying her best to get to own Heaven and take over God and she is a massive manipulator. Yes, but You Decide.