Tayvor Slen, a male Human and a citizen of the Eternal Empire originating from Zakuul, was the parent of Alianna Slen.
Slen held the position of administrator within the Overwatch, a facility that managed the control systems for more than half of the droids present in the Spire. His combat abilities served as a template for the creation of the Skytroopers. In the year 3632 BBY, Kaliyo Djannis, an anarchist, made her way to Zakuul and, under the alias "Firebrand," initiated a series of bombings targeting both civilian and military locations, which garnered her a substantial following. Ultimately, Tayvor managed to persuade Kaliyo to restrict her bombings to only unarmed targets in return for his promise to shield her from the skytroopers, an offer Kaliyo accepted due to her frustration over her inability to genuinely shock the Zakuulans. Nevertheless, she exploited both Tayvor's growing romantic feelings for her and his daughter's involvement among her followers as a means to undermine Zakuul.
Following the Commander's release from carbonite in 3631 BBY, which resulted in a widespread power outage during the escape, Kaliyo commenced planting bombs throughout the city while simultaneously acquiring the Overwatch data through Alianna. Eventually, the Outlander forged an alliance with Kaliyo, and together, they launched an assault on the Overwatch, placing explosives at the droid control systems. Tayvor arrived accompanied by the skytroopers and made an attempt to thwart them, but he was defeated and sustained fatal injuries during the confrontation. Before his death, Kaliyo ridiculed Tayvor's attempts to manipulate her and revealed that the destruction of the droid controls, combined with the detonation of the bombs, would trigger mass hysteria and plunge the Spire into a state of complete disarray.
Tayvor Slen makes an appearance in Star Wars: The Old Republic: Knights of the Fallen Empire in Chapter X: Anarchy in Paradise.
In a Zakuul News Bulletin announcement, his last name is incorrectly spelled as Slenn.