Darth Krayt, born A'Sharad Hett, was a Human male who served as a Jedi Master in the waning days of the Galactic Republic. The son of legendary Jedi Knight Sharad Hett and his wife K'Sheek, both of whom lived among the Tusken Raiders of Tatooine, he eventually became the Padawan of Jedi Masters Ki-Adi-Mundi, and later, An'ya Kuro. When he was only a teen, Hett's father was murdered by the Jedi assassin Aurra Sing, who was later defeated in a duel by a young A'Sharad Hett. During the Clone Wars, he served the Republic as a General and established himself as a charismatic leader who often led his troops from the front. He eventually became friends with the young Anakin Skywalker and helped Anakin come to terms with the destruction which had been wrought by the galaxy-wide war. A'Sharad took part in key conflicts during the war such as the Battle of Boz Pity and the Siege of Saleucami. He managed to survive the Clone Wars, and was one of the few Jedi known to have escaped the Great Jedi Purge in 19 BBY.

A'Sharad Hett eventually made his way back to his homeworld of Tatooine where he vowed to wage a private war against the new Galactic Empire. However, after a confrontation with Jedi Master Obi-Wan Kenobi, he was exiled from Tatooine and later discovered that it was Anakin Skywalker who became the Sith Lord Darth Vader, who he had aided in the annihilation of the Jedi Order. A'Sharad blamed himself for the destruction of the Jedi Order and became a bounty hunter. During one of his missions, he found himself on Korriban, where he trained as a Sith under the tutelage of the Dark Lord XoXaan. Hett eventually fell to the dark side after capture and torture by the Yuuzhan Vong and soon proclaimed himself Dread Lord and Dark Lord of the Sith, taking the name "Darth Krayt".

As Krayt, he became the founder and leader of the One Sith. He rebuilt the Sith Order and kept its existence hidden from the Jedi by cloaking their presence on Korriban. To survive, the Dark Lord spent many years in stasis before reemerging to form an alliance with Moff Nyna Calixte and to spark the Sith–Imperial War that led to the destruction of the Galactic Federation of Free Alliances. At the climax of the war, he deposed Emperor Roan Fel and brought about the destruction of the New Jedi Order.

Darth Krayt ruled the galaxy with an iron fist for seven years before the alliance between rightful Emperor Roan Fel and Galactic Alliance admiral Gar Stazi threatened his usurped rule. Furthermore, Krayt discovered the existence and survival of a Skywalker: Cade. Krayt feared that with these deteriorating conditions and his bad health would lead to his demise before his dream was finished, and sent about the hunt for Cade Skywalker. However, during a skirmish on Had Abbadon, Krayt was stabbed and sent hurtling off a cliff. The Sith Lord's powers proved strong, however, when they saved his life. Darth Krayt was then approached by Darth Wyyrlok, his most trusted advisor, who presumably murdered Krayt, believing the Dread Lord would lead to the Sith Order's destruction.

But, even as he was inactive, Krayt's ideals were being carried out by Wyyrlok in his place. Krayt later healed his body from his near-death experience. Overcoming the taint of his armor, he called out to all those across the galaxy who had touched the dark side, signaling his return. With the aid of loyal Sith and a new breed of Sith troopers, Krayt retook Coruscant, slaying Darth Wyyrlok in the process, and began making preparations to rebirth the galaxy through war. However, in the final battle, he once again attempted to turn Cade Skywalker. He failed to do so, which allowed Cade to permanently kill him.

Darth Krayt should sound like Christian Bale, Karl Urban, or Guy Pearce.

Christian Bale Example: https://www.youtube.com/watch?v=mKw-w1LWfxQ

Guy Pearce Example: https://www.youtube.com/watch?v=6_5rouEoTuY 

Karl Urban Example: https://www.youtube.com/watch?v=8j_qTgMGgfM