A tactical drone was a type of drone utilized in the Borg Collective, some of which possessed a tritanium infrastructure.
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 it's species was Ktarian, known to the Borg as Species 6961. (VOY: "Dark Frontier")
Hazari also made excellent tactical drones due to their violent nature and advanced technical abilities. (VOY: "Think Tank")