Warcraft is a multimedia franchise created by Blizzard Entertainment. Originally Blizzard's attempt to make Warhammer, but better, the series started as a real time strategy game before redefining what "big time" meant with World of Warcraft. Along the way there have been comics, novels, a trading card game, and an infamous cancelled adventure game.
The series primarily takes place on the planet of Azeroth, home of humans, dwarves, elves, trolls, and dragons, with occasional trips to Draenor, or Outland, home of Orcs and Draenei. As the title suggests, most of the races are usually at war with the others, the cause of which are old grudges started back when one race or another was possessed by demons from beyond. Over the series' long history it has amassed a large collection of heroes and villians, all of which are being slowly killed off thanks to continuous expansions of the MMO.
A personal servant of Queen Azshara, she was present at The Sundering and was also chosen to be the first Naga envoy to the surface world millenia later in Warcraft 3. There she met the Night-Elf Demon Hunter Illidan, and chose to join his fight against the other Night-Elves. She eventually followed Illidan across the world and into Outland, choosing to stay by his side after he successfully overthrew its demonic occupiers. She was still an aide of Illidan in WoW: Burning Crusade where players were able to attack and kill her as a raid boss in her underwater fortress.
Like most female Naga Lady Vashj was a skilled archer, and could also cast lightning magic.
The Naga were former Elves, created when Queen Azshara's plan to bring the demonic Burning Legion into Azeroth was foiled and the Well of Eternity exploded. The force of the explosion, known as The Sundering, was enough to split the single continent into parts, with the Highborne Elf capital left at the bottom of a newly formed ocean. Azshara quickly formed a pact with the Old Gods, saving her people but transforming them into aquatic, reptilian forms.
Male and female Naga have significantly different physiques: while males have two arms and a burly physique, females are thin, have four (or more) arms, and are fequently spellcasters.
Originally queen of the Elves, Azshara changed along with the rest of her new Naga race because of her pact with the Old Gods. Although she is still the undisputed ruler of the Naga, she has yet to appear, post-Sundering, in any official Warcraft media.
Succubi are common forces in the demonic legion, as well as being a low-level summon for warlock player characters in World of Warcraft. They specialize in annoying their targets by cursing and stunning them. They're probably also into S&M play if their voice quotes are anything to go by.