Mandalore the Ultimate is a major antagonist in the Star Wars franchise. He serves as the main antagonist of the Knights of the Old Republic comic book series.
He was the leader of the Mandalorian clans serving as Mandalore and was one of the last of his kind, the Taung, to claim the title of Mandalore. He was originally a member of the Mandalorian Crusaders and later reformed them sometime after the Great Sith Wars where he reunited the Mandalorian Clans and restored their military power and influence across the galaxy.
After he reformed the crusaders into the Mandalorian Neo-Crusaders, he lead them to war and instigated the Mandalorian Wars where he and his followers waged a galaxy-wide war against the Galactic Republic with the intent on destroying the Republic and making the Mandalorians the most feared and powerful army in all of galactic history.
During the war, he invaded and conquered countless worlds and laid waste to countless cities, killing billions if not trillions of beings forcing rogue members of the Jedi Order to defy the orders of the council and intervene in the war to stop Mandalore and his armies.
Little is known about the Taung's life prior to becoming Mandalore the Ultimate and assuming supreme authority over the Mandalorian clans, but what is known is that he was the quickest Mandalorian to ever master the use of Basilisk war droids. During the last days of the Great Sith Wars, he was part of the Mandalorian invasion of the planet Onderon. The invasion saw the Basilisks pinned up against Beast Riders lead by the Onderonian King, Oron Kira, who ended up repealing the Mandalorian invaders and pushed them back to the harsh moon of Dxun.
During the evacuation to the planet, Mandalore the Indomitable was killed by the beast-infected jungle and a search party was sent out. Mandalore the Ultimate would stumble across his body, claimed the mask himself and took his place as the new Mandalore.
In the years following the death of Mandalore the Indomitable, the his successor would go on to prove himself worthy of the title "Ultimate" as well as the title of Mandalore which made him the leader of the Mandalorian clans. In the wake of the devastating defeat of the clans, Ultimate had set his sights on rebuilding and reforging the clans into a powerful and merciless army that would spread fear throughout the galaxy.
He understood the importance that a harsh environment such as Dxun had to training warriors and used it to his advantage as he had a training complex built and used it to train new Mandalorian warriors to rebuild the Mandalorian armies. Mandalore the Ultimate had thus established the moon as the new base of operations for the Mandalorians as they rebuilt and recalled the disparate clans.
Despite few had remained to heed his summons, Ultimate was undeterred and instead, he began recruiting new warriors from other species, greatly reforming the culture and identity of the Mandalorians and trained a new generation of Mandalorians and formed the Mandalorian Neo-Crusaders. In time, the Mandalorian ranks had swelled up greatly and composed countless warriors from various different worlds and species with humans making up the majority of the Neo-Crusader ranks along with other species like Rodians, Twi'leks, Togorians, Kerestian, and Mandallian Giants.
Under Ultimate's direction, the term Mandalorian took a new direction and was no longer just a species, it was a unifying warrior culture dedicated to earning glory and honor through combat.
Revan and Malak's Sith Empire