Three of Five, a Borg tactical drone, being studied by the Hansens.
A tactical drone was a type of drone utilized by the Borg Collective.
During their expedition to locate and study the Borg in the early 2350s, the Hansens managed to beam a tactical drone onto the USS Raven for examination. They determined its species was Ktarian, known to the Borg as Species 6961. Tactical drones possessed a tritanium infrastructure.(VOY: "Dark Frontier")
Hazari also made excellent tactical drones due to their violent nature and advanced technical abilities. (VOY: "Think Tank")