|Occupation:||Dark Templar Leader|
Zeratul is the Leader of the Dark Templar and a wise and powerful leader. His planet that he now lives on is called Shakuras. He tends to use his wits and common sense more than other Protoss. He has little love for the Protoss Conclave and the Templar because of their persecution years ago but reluctantly helps them for the sake of his home planet Aiur. He has helped save the the galaxy on multiple occasions but also put it in danger by unknowingly revealing the location of Aiur to the Overmind which would eventually lead to its destruction. He was also deceived by Sarah Kerrigan as were the rest of the Protoss which eventually lead to Zeratul being forced to take the life of his own mentor Raszagal. He carries this guilt as he helps in the fight for the survival of the Protoss.
 During Broodwars
During Broodwars, Zeratul is seen as the new order in replacement for the Tassadar due to his death. It's notes that while Zeratul isn't as strong or wise as Tassadar (as he stated in a cut scene) that he gladly takes upon the role that Tassadar took to prevent the Overmind from destroying the universe. Zeratul is a strong and wise Protoss himself, which he shows in the constant combat put through him in the Protoss Campaign in Broodwars. He proved that he was worthy of the position that Raszagal place upon him upon her death as Leader of the Dark Templar. Zeratul holds a big grudge against Kerrigan for leading to Raszagal's death and swears vengeance upon Kerrigan for the death of the Dark Templar leader.
You'll first meet Zeratul on the planet Aiur after destroying the Overmind. Zeratul with be partnered up with another protoss called Artanis and has to help the protoss refugee's get to the warp gate to reach the planet Shakuras to find the other Dark Templar. But, however the zerg have already made their way to the planet and you must fight them to get to the other Dark Templar. After meeting up with Raszagal, you will quickly be sent on a mission to retrieve the crystals Khalis and Uraj, but before you can search for them, you must first destroy the zerg that lay around the Xel'Naga temple. After the fight, you will meet up with the self proclaimed Queen of Blades (Kerrigan) and she will ask for your help in exchange for helping you gather the crystals. Zeratul doesn't like the idea, but the Matriarch agrees with Kerrigan, and Zeratul promptly changes his attitude. After you have gotten both crystals, Aldaris will cause an uproar and has the protoss refugee's from Aiur band together against the Dark Templar. Raszagal ordered Zeratul to terminate Aldaris and quell the uproar because the zerg could attack at any minute. Zeratul is quite disturbed by this because he's know the Matriarch to be a kind and gentle soul, however he complies. After fighting through the protoss forces, they confront Aldaris who attempts to reveal that Raszagal is under the control of Kerrigan. But before he can revealing the information, Kerrigan and two Lurkers kill him. Zeratul banishes Kerrigan from the planet, forever. Now Zeratul and Artanis must take the crystals to the Xel'Naga temple, and place them in at the top. However, the zerg have surrounded the temple on all sides. Both Zeratul and Artanis fight their way through and activate the temple, which sends out a powerful wave of energy that destroys all the zerg. The protoss are safe from the inpending doom of the zerg, for now. Zeratul then is shocked as the Matriarch is kidnapped by Kerrigan. He goes to find Kerrigan who forces him to destroy the new Overmind so that she can have full control over the zerg. He and the rest of the dark templar destroy the new Overmind, giving Kerrigan full control over the zerg. Zeratul then demands the return of the Matriarch, and Kerrigan asks her if she wants to return. The Raszagal says no, which shocks Zeratul. He then knows that Raszagal is under the control of Kerrigan. He then sneaks into her lair and steals the Matriarch away, and heads for the warp gate that will take them home to Shakuras in 30 minutes. But, during this time Kerrigan destroys all the protoss but Zeratul and Raszagal that have followed Zeratul to Char. Fearing the worse, Zeratul kills the Matriarch. He says that it's bettet for her to be dead than in the hands of Kerrigan. Kerrigan allows him to live, saying that she's already done enough damage to his glory saying. Zeratul leaves, angry and swear vengeance against Kerrigan. Zeratul then finds a protoss signal coming from a dark moon. He follows the signal, and meets the most unlikely of people; Samir Duran who appears to have created some type of protoss zerg hybrid. With the information that Duran reveals to Zeratul, it frightens him. Zeratul leaves the planet, disturbed at what will come.
It is unknown if Zeratul has a placement amongst the main characters in StarCraft II, however we do not doubt that he will be a main character being the attendant of the character you be playing as during the Protoss Campaign in StarCraft II.