The Hive Father was swarm of Vashta Nerada that had concentrated on a human host, taking over his body to further assist in the devouring of Gregorae in the 27th century. It is unknown who they infected, but the Doctor speculates it to have been a figure of high authority.
The Hive Father is an extremely intelligent and powerful being, seen as the amalgam of the Vashta Nerada's hunting instinct and insatiable hunger with the genius of the human mind. With this new found power the massive swarm on Gregorae have plans to spread outward through the universe, with the Hive Father leading them. It displays a variety of powers, such as extending itself to pass through doors, over buildings and through air vents, making escape from it highly unlikely.
When shot or struck, it breaks wherever it has been damaged but reforms rapidly. It is unknown how it consumes its prey, but it is believed a touch is enough of devour an entire human as the swarm simply overpower the quarry. The Hive Father can also animate other humans, dead, and use them as soldiers.