Banshees were once elf women, returned to a horrible, spectral existence. When the Burning Legion and the kaldorei clashed in the War of the Ancients, 10,000 years ago, many night elf women fell. Their brutal murders returned them as banshees, and for millennia they wandered the world in lamentation, losing ever more of their dwindling sanity. Eventually, the Lich King, Ner’zhul, learned of their existence and recruited them into the Scourge. Banshees fought in the Third War alongside other undead, and when Arthas attacked Quel’Thalas, he found that he could make banshees of high elves as well.

Banshees are undead spirits, many of them from High Elves who were taken and enslaved by the Lich King after his conquest of Quel’Thalas. While under Ner’zhul’s control the banshees were kept just aware enough so that they could experience the pain, desperation and anguish of their existence, and were then filled with a desire to spread that pain among the living. Most known for their chilling and deafening screams, banshees can also cast a number of curses.

After the Third War, the Lich King lost control of some of the banshees, including their queen Sylvanas Windrunner. Not long after Arthas raised her as a banshee, she broke from his control, taking fellow banshees with her. She regained her physical body and established the Forsaken. This act gives many banshees hope, and a strong cadre of free banshees can now be seen serving with the Forsaken. Most banshees still remain enslaved to the Lich King’s will though, and can be found throughout the Plaguelands. Many wild, unafilliated banshees exist as well. Physically, they appear as spectral elven women, with wild flowing hair and long talon-like hands. Banshees have the unsettling ability to force their way into the bodies of living creatures, thus replacing the creatures’ spirits with their own. A banshee who does this, however, loses its original form.

It is thought that some banshees wandered Azeroth long before the Scourge, and were subjugated to the Lich King’s will. This is supported by the presence of Banshees in ancient Kaldorei ruins throughout Kalimdor, like Dire Maul.

Relation to Dark Rangers: Sylvanas Windrunner, the first banshee ever created by the Scourge, later regained her physical form to become a Dark Ranger. It is not explained how exactly this occurs, but it is implied that it had to do with Sylvannas replacing former elven ranger druidic knowledge with necromancy.

Sylvanas’ dark ranger form has been compared with dark elves by some fans, a race thought to have been the basis of her physical form, however this is unconfirmed. Though its partially implied in Horde Player’s Guide, where dark rangers are considered cousins to high elves, and the idea of converting to “dark” is given. Dark elves do not exist in the Warcraft Universe as such, though Ul’haik Hadanot is an example that the potential for a similar race is possible.

Non-elven Banshees?: Although uncommon, it appears possible for human women to become banshees upon their undeath. Blind Mary and Nissa Agamand are examples of such. It is possible that these women have some elven blood dating several generations back, and that it is this that causes them to become banshees. Their undead model appears fully elven like other banshees. According to Alliance Player’s Guide, descendants of half-elves from multiple generations are still half-elves, so this is unlikely. However, it may be just a matter of Blizzard not making special in-game models for those characters, and they are in fact just ghosts.