The title of Secret Mandalore was a designation taken on by the head of the extremist Mandalorian faction known as the Death Watch. These individuals, also called the Death Watch Overlord, believed they were the rightful inheritors of the traditional title of Mand'alor, the leader of all Mandalorian people and clans. They opposed both the "Anti-Mandalore," who governed the pacifist New Mandalorian society, and the "True Mandalore," who was selected by the members of the mainstream Mandalorian warrior clans.
During the early years of the Clone Wars, Pre Vizsla outwardly served as the governor of Concordia, one of Mandalore's two moons. However, in secret, he was the latest leader of the radical Mandalorian splinter group, Death Watch. Vizsla held the pacifistic New Mandalorians and their leader, Duchess Satine Kryze, in contempt. He firmly believed that the Mandalorians' destiny was to reclaim their ancient role as conquering warriors. To achieve this, Vizsla allied Death Watch with the Confederacy of Independent Systems during the Clone Wars. He pledged his support in exchange for the Confederacy's leader, Count Dooku, assisting him in removing Kryze from power. Despite their attempts to provoke the Galactic Republic into taking action against Mandalore, hoping that a Republic occupation would spark a violent rebellion among the New Mandalorian population that would then rally to Death Watch, Kryze successfully prevented the Republic's plans for occupation. She achieved this by speaking before the Galactic Senate on Coruscant, thus thwarting Vizsla's schemes. Eventually, Death Watch was banished from the Mandalore system, and Pre Vizsla had a falling out with Dooku, which resulted in a facial scar and an intense hatred for the Confederate leader. Vizsla then led the now-nomadic Death Watch across the galaxy, settling on the snowy planet of Carlac, before relocating to the swampy moon of Zanbar.
During one of Death Watch's journeys, Vizsla encountered the Sith Lord Darth Maul, and through the Zabrak Sith, he discovered a new way to overthrow the New Mandalorians' pacifism. Vizsla forged an alliance with Maul, and together they created a criminal organization known as the Shadow Collective by enlisting members of Black Sun, the spice-dealing Pyke Syndicate, and the soldiers of the Hutt Cartels. With their army of criminals, Vizsla and Maul initiated a plan to overthrow the New Mandalorian government. The Collective's gangsters would attack the New Mandalorian capital city of Sundari, creating chaos and making Duchess Kryze appear weak in the eyes of her people. Then, Death Watch would arrive to rescue the New Mandalorian citizens from their attackers, gaining public support. The plan unfolded as intended, with the New Mandalorian police unable to withstand the sheer number and firepower of the off-world criminals. The New Mandalorian people sought help from an administration that was powerless to protect them, and order was only restored when Death Watch intervened to combat the criminals overrunning Sundari. With the people's support, Pre Vizsla stormed the Sundari Royal Palace and had Kryze arrested. The Secret Mandalore of Death Watch then assumed his position as the new leader of the New Mandalorians. However, Vizsla's time as Mand'alor of the New Mandalorians was short-lived. Once he had achieved his goals, he betrayed his Sith ally and attempted to have Darth Maul incarcerated. Maul escaped his confinement and challenged Vizsla to a fight to the death for leadership. Despite Vizsla's fierce resistance, utilizing the full arsenal provided by his Mandalorian armor, he was defeated and killed by Maul, who declared himself the new leader of Death Watch and Secret Mandalore.
Maul, who was born on Dathomir, was trained from a young age as a Sith by the Dark Lord of the Sith Darth Sidious. Upon becoming Sidious' Sith apprentice and earning the title of Darth, Maul became a formidable force in his master's plan to conquer the galaxy. However, his time under Sidious was cut short when, in 32 BBY, Maul was severely injured by the Jedi Obi-Wan Kenobi on Naboo. Severed in half at the waist, Maul was kept alive only by his hatred and the power of the dark side of the Force. He spent years in squalor on a garbage-covered world where his body had landed, until his estranged brother Savage Opress found him, half-insane. Opress brought Maul back to Dathomir, where his mind was restored and his body was rebuilt with cybernetics by the Nightsister Mother Talzin. With his faculties restored, Maul sought revenge on Kenobi, taking Opress as his own Sith apprentice.
Maul's pursuit of revenge led him to form an alliance with the radical Mandalorian group Death Watch and their leader, Pre Vizsla. Seeing their combat skills and efficiency as valuable assets, the Sith agreed to help Vizsla overthrow the pacifist New Mandalorians. Together, they gathered a group of criminals from Black Sun, the Pyke Syndicate, and the Hutt kajidics, and unleashed them on the New Mandalorian capital of Sundari to spread fear and chaos and undermine the pacifist government. As the people panicked, Death Watch stepped in to stop the criminals, putting on a show for the public and gaining their favor. The New Mandalorian leader Satine Kryze was disgraced and deposed, and Pre Vizsla took her place, only to immediately turn against Maul and his apprentice. Unbeknownst to Vizsla, Maul had anticipated his betrayal. The Sith Lord challenged Vizsla to a duel for leadership, killing him and declaring himself the new Secret Mandalore in charge of Death Watch. Maul's leadership was challenged by members of Death Watch loyal to Vizsla's lieutenant, Bo-Katan Kryze, who refused to follow a non-Mandalorian like Maul. They broke away from those who swore allegiance to the Sith Lord. Maul reinstated the former Prime Minister Almec to serve as a puppet ruler of the New Mandalorians, allowing him to control both factions while remaining hidden from the galaxy. Despite this, Maul's former master, Darth Sidious, tracked his former apprentice to Mandalore. There, he engaged Maul and Savage Opress in a lightsaber battle that resulted in Opress's death and Maul being defeated by the Dark Lord of the Sith for his own purposes.
After Death Watch splintered and turned on itself following Maul's rise to power, Lorka Gedyc established a new version of Death Watch, assuming leadership of the group by 19 BBY. Gedyc held the Mandalorians of old in high regard, those who had forged an empire spanning vast regions of the galaxy. The diminished state of the Mandalore sector was appalling to Gedyc, and he believed that the Mandalorians' reliance on mercenary and bounty hunting work was akin to scavenging for scraps. Following the Republic's reorganization into the Galactic Empire, Lorka Gedyc saw an opportunity to restore the glory and power that Death Watch believed the Mandalorians had lost. Gedyc allied Death Watch with the new Empire and instructed Death Watch members Dred Priest and Isabet Reau to help the Imperials establish their garrison on Mandalore, just outside the planetary capital city of Keldabe in the "City of Bone." Priest admired Gedyc and his plans, but he was killed for his ties to the radical sect by fellow Mandalorian Mij Gilamar, and the Empire ultimately moved to enslave Mandalore and its people.
By the year 1 ABY, with Mandalore firmly under the control of the Galactic Empire, a remnant of Death Watch had escaped to the forested moon of Endor. Operating from a secret underground bunker, they were led by a Human male Mandalorian who used the title of Overlord. From the bunker, the new Overlord commanded a force of Death Watch Wraiths, Ghosts, and Bloodguards, and rekindled Death Watch's relationship with Black Sun from the Clone Wars, contracting with the syndicate's assassins in exchange for their help in advancing Death Watch's goals.
Although Death Watch had faded into obscurity, word of their survival on Endor eventually reached Imperial Commander D'krn on Tatooine. He believed that the Death Watch Overlord could be a promising candidate for a new generation of cloned stormtroopers, just as Jango Fett had been for the former Republic's Grand Army. To that end, D'krn hired a group of spacers to obtain a sample of the Overlord's blood. The survival of Death Watch on Endor had also come to the attention of Boba Fett, who was working for Jabba the Hutt on Tatooine at the time. As the son of Jango Fett, who had fought Death Watch to near extinction decades earlier, Boba Fett wanted to see the splinter group eliminated once and for all. He offered assistance in breaching the bunker and payment to the spacers if they killed the rogue Mandalorians. The spacers eventually attacked the Endor bunker, killing many Death Watch troops, including their Overlord, before returning to D'krn with a vial of his blood.
Death Watch and its leader were first introduced to the Star Wars universe with the release of the Jango Fett: Open Seasons series, which was written by Haden Blackman and published in 2002. A year later, in 2003, the Star Wars Galaxies video game released an update called "An Empire Divided," which featured a new Death Watch leader in the Imperial era, holding the title of Overlord. The Republic and Imperial Commando series of novels by author Karen Traviss, as well as the Star Wars: The Clone Wars television series, also introduced other leaders of Death Watch during and after the Clone Wars. However, it wasn't until the 2013 release of The Bounty Hunter Code reference book by Jason Fry, Daniel Wallace, and Ryder Windham that the Death Watch leader was officially given the title of Secret Mandalore.