The Turok-Han are a species of demon vampire native to the Sunnydale Hellmouth. While thought to be only a myth to the Watcher’s Council by 2003, they still existed beyond the mortal plane, waiting for their moment.
They were servants of the First Evil and worked in tandem with the Harbingers of Death in order to bring forth armageddon by killing all of the Potential Slayers, eventually murdering Buffy Summers and Faith Lehane, which would therefore end the Slayer line and leave Earth without any kind of guardian.
In 2002, the First Evil orchestrated the summoning of one by using the blood of the captured vampire hero Spike on the Seal of Danzalthar, which released it from the Hellmouth. Upon its arrival, it was used by the First Evil to routinely attack and terrorize Buffy, while also torturing Spike when it was daytime.
During her first encounter with the First Evil’s champion Turok-Han, Buffy was caught off-guard and severely wounded during the fight. Despite her quick defeat, it should be noted that she had been deprived of any sleep or rest for two consecutive days, so her performance was very hindered. Eventually, it hunted and murdered the Potential Slayer Annabelle, leaving her cross necklace behind as evidence.
Eventually, Buffy managed to orchestrate a plan with her friends Xander Harris and Willow Rosenberg in order to lure the Turok-Han to an abandoned construction site. There, Buffy outsmarted and overpowered the creature, ending the encounter by decapitating and dusting it in front of the remaining Potential Slayers.
The demon Lissa tried to open the Seal of Danzalthar again in order to summon one, seducing Xander in order to sacrifice him. She nearly succeeded, but she was killed and the Turok-Han was imprisoned again before it could escape.
When Buffy visited the Shadowmen, they showed her a vision of the true danger: thousands of Turok-Han waiting under the Hellmouth. It was then that Buffy knew that she and Faith would not be enough.
A few weeks later, at least three more were released, likely due to the efforts of Caleb.
During the Battle at the Hellmouth, Willow used the mʔ to activate all of the Potential Slayers so that they could fight the army under the Hellmouth. While they were being pushed back, they eventually won due to the sacrifice of Spike. After this event, the Turok-Han were completely annihilated.
