Diablo

Diablo is a multimedia franchise created by Blizzard Entertainment. The world of Diablo is constantly being fought over by angels and demons, and by the humans who have taken sides. Neither side is exactly friendly with humanity, but the demons are usually the more immediate threat.

Andariel
Andariel was one of the four lesser evils who overthrew the three rulers of Hell and banished them to Earth. After Diablo got loose and started looking for his brothers Andariel headed up to the surface to try and bind him up again, as well as just cause general havok. To that end she took over the monastery of the Sisters of the Sightless Eye, corrupting any sisters unfortunate enough to not to escape. Andariel was eventually slain by the protagonist(s).

Cydaea
Cydaea is a minor demon whoa appears as a boss in Act IV of Diablo III. Her most dangerous attack is flooding the area with minions that the heroes must slay to remove her shield.

Diablo
Diablo, one of the three Prime Evils, is the recurring antagonist of all of the Diablo games. At the end of Diablo III, for some reason (perhaps because he had just possessed the body of a woman, perhaps because he had merged with the 6 other Evils, or perhaps because Blizzard just felt like it), Diablo has a feminine form for this incarnation.

Lilith
Lilith is a minor demon who appears in the novel Sin War as well as a minor appearance in Diablo II. In Sin War she attempts to exploit a human king to summon the armies of hell, but her human disguise is dispelled at the last minute, revealing her for who she truely is. In the novel she is described as green-skined with reptilian scales.

In Diablo II she appears as a black pallet-swapped Andariel in the battle.net Pandemonium event. She fights no differently from Andariel.

Succubus
One of the most powerful of the demons under the command of Diablo, Succubi are found in the deepest reaches of Tristram's dungeon in Diablo. They attack by shooting blood stars.

They later return in Diablo II, though with a more avian design. They show up late in the game, in Act V.

Succubi also appear in Act III & IV of Diablo III. Fittingly they serve Cydaea, Maiden of Lust.