Belial

From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide

Belial is an IL-series Cylon.

Belial, seeking a way to further the advances of the Cylon Empire, believed that returning to its biological form was necessary. He created the nano-cybrid to further this aim, but was apparently captured before he could refine his work.

As a result, the basestar and Belial's followers were destroyed (Battlestar Galactica: Cylon Apocalypse 1), and the nano-cybrid eventually fell into the hands of the Colonials on Galactica.

The Colonials weaponize it for an attack on Tessida, where Belial is held, partially disassembled and bound by Viceroy Abbadon to await his fate with the other Cylons under imminent attack (Battlestar Galactica: Cylon Apocalypse 3).