Druk's planet of origin is unknown. However, at some point it was conquered by the forces of Ming. Recognized as having a brilliant scientific mind, Druk was subsequently spared and brought to Mongo to work in Ming's laboratories and to help develop weapons of mass destruction.
Although Druk undertakes such work and feigns loyalty to Ming, he has constantly been awaiting an opportunity to avenge his people, most of whom were destroyed. At some point he befriends another fellow scientist named Karm, who is also held prisoner and the pair exchange what information they can whenever the attention of their guards is diverted.
Although Karm is eventually killed by Ming, Druk's chance for salvation finally comes when he meets Doctor Zarkov, when the Earthman is recaptured and put to work in the same laboratory. Zarkov had also worked with Karm and quickly forges an understanding with Druk.
Druk helps Flash Gordon and Dr Zarkov escape Ming's palace and steal the Z-O rocket ship, bravely staying behind alone to control the death rays which guard the Space Court. Druk does this on the understanding that he will be killed when the Z-O ship is aimed at the palace. Luckily, Druk gets to live a while longer, as ultimately only the tower of the palace is destroyed once Ming takes refuge there.
Druk was portrayed by actor Byron Foulger.