Darth Rivan, a Zelosian by birth, achieved notoriety as a Sith Lord during the era of the New Sith Wars. He adopted his Sith designation from a flawed Sith document; this document erroneously identified Darth Revan, the Dark Lord of the Sith who found redemption during the Jedi Civil War, as "Rivan."
In the course of the New Sith Wars, Darth Rivan journeyed to the unexplored Cularin system and established a presence on the planet Almas, despite the planet's unaccommodating environmental conditions. It was there that he erected a fortress, with the intention of probing the enigmas of the dark side.
However, Rivan's real motivation behind the fortress's construction was to bring Sith battlelords into existence. Rivan's conception of this new, select group was rooted in the very essence of the dark side, particularly its intrinsic disharmony. The gathering of numerous darksiders in a single space inevitably led to conflict, with some meeting their demise or turning against each other. Harmonious collaboration was not a value espoused by darksiders. Rivan made it his mission to eradicate disloyalty within the Sith ranks, and his creation of the battlelord served to Force bond a commander to their troops—if a soldier attempted to injure their commander, the harm would, instead, befall the soldier themselves.
Analysis of the fortress, conducted shortly after the Battle of Naboo, indicated that the dome atop the fortress was significantly aged, exceeding 1,000 years. The fortress itself functioned as a massive dark side nexus, capable of discharging lightning at passing starships.
The castle was riddled with mechanical traps, undetectable by either the Force or advanced technology. Rivan employed Mandalorian iron, a material resistant to both the Force and lightsabers, to safeguard his most cherished texts and as the flooring for his lightsaber training area. Furthermore, he engineered the fortress to isolate his slaves/captives (including at least one Jedi) from the Force, inducing feelings of utter disorientation and despair. Darth Rivan inscribed his autobiography in Sithese within the inner walls of his stronghold.
Darth Rivan gained recognition as the possessor of the potent artifact known as the Darkstaff, a semi-sentient weapon with the ability to drain the Force-essence from living beings.
Darth Rivan was also responsible for engineering kaluthin grass to alter the planet's environment and atmosphere, rendering it breathable. While kaluthin transformed Almas into a garden-like setting, it failed to eliminate the harmful native gases, ensuring that Almas's atmosphere remained less than pristine.
Rivan resided on Almas for several decades until he was driven away by the Jedi Knights sometime before 1250 BBY. During the Battle of Almas, the Jedi forces demolished Rivan's fortress structure, although the central tower, impervious to blaster fire, survived the assault.
Ultimately, Rivan's pursuit of physical immortality proved unsuccessful. Initially, it was believed that Darth Rivan narrowly escaped with his life after being ousted from Almas by a large-scale Jedi/Republic offensive, eventually meeting his end after being betrayed by his fellow Sith, specifically his apprentice, Darsin.
However, the truth was that Rivan departed from the fortress one day, leaving Darsin behind. Darsin perished before Rivan, his body altered by Rivan's alchemical processes to create a slave Force spirit. Rivan successfully harnessed the power of the Darkstaff to generate a Force storm that propelled him through time and space to the planet Ruusan, during the conflicts between the Jedi Army of Light and the Sith Brotherhood of Darkness several centuries later. There, with his Force abilities depleted by the Darkstaff, he was easily defeated by a Force-user of negligible power. Rivan was unable to be entombed in the crypt he had constructed for himself.
Fragments of Rivan's journals were unearthed and recovered from his Almas fortress during the Clone Wars, and subsequently presented to the Jedi Council on Coruscant for analysis.
Rivan was well-regarded due to his capacity to create Sith battlelords. Within his fortress, Rivan demonstrated his dedication to studying and mastering the dark side. Rivan's most prominent achievement was the creation of kaluthin grass to modify the atmosphere of the planet Almas, rendering it breathable.
Rivan is the last known Darth in chronological order before Darth Bane. Initially, Bane was thought to have originated the title, as no earlier Sith Lords were known to have used it at that time. It was later discovered that the title "Darth" originated during the Mandalorian Wars, or even earlier. Darth Rivan lived prior to Bane, the originator of the Rule of Two. Nevertheless, a trap within Darth Rivan's fortress, as depicted in A Mon Alone, reflects the Sith's adherence to the Rule of Two.
Rivan has not appeared or been mentioned in any actual narrative. Thus far, both he and the Almas fortress have only been referenced in supplementary books and role-playing scenarios.