Vasco Nailhead, also known as Vas, held the position of leader within the Bone Kings, a significant prison gang operating inside the Cog Hive Seven correctional facility. He was a male Human, and his leadership occurred around 33 BBY.
Prior to the Naboo crisis, Nailhead's criminal activities led to his incarceration at the Cog Hive Seven prison station. There, he ascended to the leadership of the Bone Kings gang, which at one point consisted of sixteen members. The Bone Kings were rivals with the Gravity Massive, which was led by the Noghri named Strabo. Unbeknownst to many, both gangs were secretly supporting the arms dealer Iram Radique. Radique had established a vast network of associates within the prison and conducted his illicit operations from a hidden location within the facility. Nailhead had consistently triumphed in the prison's daily gladiatorial contests, earning a reputation as a merciless cannibal due to his habit of consuming a portion of the flesh of every living being he defeated in combat.
In 33 BBY, the Sith Lord Darth Maul infiltrated the prison under the guise of a prisoner known as "Jagannath," as part of a clandestine mission to locate Iram Radique. The Dathomirian Zabrak quickly gained notoriety by achieving victory in the mandatory gladiatorial battles held within Cog Hive Station. To instigate chaos, the Sith Lord deliberately provoked a conflict between the Bone Kings and the Gravity Massive, resulting in a violent clash. Shortly thereafter, Maul confined the two rival gangs within the Radbau Sieben washroom and nearly eliminated them using Kyrofluid. The Sith spared their lives, but compelled Nailhead and Strabo to acknowledge him as the supreme leader of both gangs.
Nailhead reluctantly submitted to Maul's authority, secretly yearning for a gladiatorial match against one of his own gang members, or even Darth Maul himself, in order to regain the respect of his fellow inmates. Nailhead's opportunity arose when prison director Sadiki Blirr permitted the Bone Kings and Gravity Massive to brutally execute a group of treacherous prison guards who were, in reality, spies working for the Hutten Jabba. This carnage attracted Syrox, a ravenous and ever-growing parasite dwelling in the prison's underground, which proceeded to consume both rival gangs, including their leaders Nailhead and Strabo.