This version of Willow Rosenberg is a vampire from an alternate dimension known as The Wishverse in the TV series, Buffy the Vampire Slayer.
She shares the same past as the Primary Buffyverse's Willow all up to one point, Buffy Summers never came to Sunnydale. Because of that, The Master took over the town, making the club known as The Bronze to become his seat of power. Sometime after Willow and Xander Harris become not only vampires, but the right hands and enforcers of The Master's New Vampire Order. They also captured and tortured Angel, the vampire cursed with a soul.
All that changed, however, when Cordelia wished to be in a world without Buffy thanks to a wish she made to the vengeance demon Anya, the Patron Saint of Scorn Women. Cordelia would find the town without Buffy was in a much worse shape. Bright color clothing were forbidden as well as staying out after dark. Cordelia would run into Xander and Willow who nearly killed her until she was rescued by a team known as The White Hats from the couple. After Cordelia told Giles about her world in which Buffy was the slayer and was sent to their town to protect it, Willow and Xander caught up with her, killing Cordelia.
The couple would go back to The Bronze to help The Master prepare the machine, a machine that is used to drain humans of their blood. Shortly after, they threw a celebration for what Xander called "The Golden Age." Then Buffy Summers of that world showed up and tries to fight the master and his order with the help of Angel. But it was all for not when Angel was staked in the battle and The Master's head was cut off. Just as Willow was about to die too, she vanished.
The Buffyverse and Death
She would appear in the Buffyverse via a spell that went wrong. She would discover that humans still rule this world's Sunnydale, that Xander was human, and Buffy was her counterpart's best friend. She then decided to remake the town in her own image. A group of vampires who works for Mayor Richard Wilkins attacks Willow and she forces them to join her.
After which she goes to The Bronze and temporally takes it over. After a brief talk with the recently depowered Anya, she went after her counterpart. Once she met her good self, she fell in lust for her. She even wanted to sire her. She refused and then Willow attacked her. Willow knocked out her vampire counterpart and they switched outfits with her.
Willow, now in the disguise of her vampiric "twin," she told her vampires to one at a time go outside where Buffy and her crew stakes them.Shortly after Anya found out for herself that she was the human Willow. Willow screamed and Buffy and the scoobies runs outside. In the meantime, Willow convinced Cordelia to let her out of her cage. She then went out to hunt for Cordelia, but was thwarted by Wesley Wyndham-Pryce.
Willow then returns to The Bronze and in the middle of battle fought her good side. Buffy would subdue her after she slayed the vampires. After which, they performed a spell to return her home. Sadly when she returned, she was happy for a while until Oz pushed her into a wooden stake. Her last words were, "Oh fu..."