I shall make dust of you. My enemies are meat for the devouring!
~ King Hydroflax

King Hydroflax is the main antagonist of the Doctor Who Season 9 Christmas special The Husbands of River Song. He is a merciless cyborg conquer who has a reputation for devouring his enemies dead or alive.


He was a large cyborg who consisted of a detachable cybernetic head and a massive robot body with an autonomous computer.


Like many tyrants, Hydroflax was cruel, mericless and extremley bloodthristy. He liked to eat his enemies flesh after killing them (earning the nickname The Butcher of The Bone Meadows) and ruled his kingdom with an (literal) iron fist.


King Hydroflax was the tyrantical ruler of The Final Cluster, which included the people of Mendorax Dellora and The Shoal of the Winter Harmony. He was infamously known as "The Butcher of The Bone Meadows" and was known to eat the flesh of his fallen enemies. Despite being a tyrant, he was revered by many of his subjects, including The Shoal of the Winter Harmony who worshiped him like a god. His bodyguards were warrior monks genetically engineered with anger issues and armed with sentient laser swords.

In the year 5343, Hydroflax led a raid on the Halassi Vaults. When the vaults exploded in the ensuring firefight, a valuable diamond called the Halassi Androvar was driven into his skull, mortally wounding him. While injured, he was taken care of by a nurse whom he fell in love with and married. Unbeknowest to him, the nurse was River Song who, along with her real husband Ramone, had been hired by the Halassi to retrive the diamond embedded in Hydroflax's skull and was willing to get it out by any means necessary.

Knowing she would intersect the Doctor's timestream on the human colony planet Mendorax Dellora on Christmas day, River crashed Hydroflax's ship on the outskirts of a small settlement.

River then sent a native named Nardole to find a surgeon to remove the diamond and ends up finding the Twelfth Doctor. However, River does not recognize the Doctor when she sees him as she believes that he used up all his regenerations and had died in the Battle of Trenzelore, unaware that the Time Lords had given him a new regeneration cycle.

River then introduces the Doctor to Hydroflax and explains the situation to him. All the while, the Doctor is frustrated by River's flirtations with Hydroflax. River then takes the Doctor aside to discuss the operation he is supposed to be performing and reveals that she wants him to remove Hydroflax's entire head and kill him in the process, considering it quicker and easier, plus it would end his reign of terror for good.

Unfortunately, Hydroflax was listening to their entire conversation and is enraged that his own beloved wife would betray him. He then proceeds to remove his head from his mechaical body to prove a point and orders his guards to kill River and the Doctor.

The Doctor uses his quick thinking and grabs Hydroflax's diembodied head, threatening to throw it down a garbage disposal shute unless they stop their attack. The pair put Hydroflax's head in a bag and are teleported out of the ship by Ramone. All the while, Hydroflax threatens the pair, saying that they will not go unpunished and will be meat for his devouring. Eventually though, his head deactivates.

Back on Hydroflax's ship, the cyborg's mechanical body activates its autonomous computer which immediately begins to seek out its head. Believing Nardole to have information about River and the Doctor, Hydroflax's body proceeds to question him before decapitating him and using his head as his own.

River, the Doctor and Ramone find the TARDIS and are just about to leave when Hydroflax's body lures Ramone into a back alley using Nardole and proceeds to decapitate and assimilate his head as well. Hydroflax's body then locates the head inside the TARDIS when the Doctor reactivates it. The pair try to take off, but are unable to because the TARDIS's safeguards prevent it from doing so when it detects that Hydroflax’s head and body are both inside and outside the TARDIS respectively. Hydroflax's body then forces its way into the TARDIS and tries to kill the Doctor and River. Luckily though, with both Hydroflax's head & body now in the TARDIS, River is able to activate the take off and fly the TARDIS. She pilots the TARDIS to The Harmony and Redemption, an intergalactic cruise ship for wealthy mass murderers.

They lock both the TARDIS & Hydroflax's body in the ship's baggage hold and request Flemming, an insectoid alien who is an old friend of River and the Maître d’ of the ship's restaurant, to deadlock seal it.

They take Hydroflax's head in the bag (during which he continues to threaten the pair until deactivating again) to the ship's restaurant where River reveals that rather than return the diamond to the Halassi, she intends to sell the diamond to a buyer named Scratch, a member of the The Shoal of the Winter Harmony, in exchange for a Universal Bank Transfer Device. Scratch had also secretly filled the meeting point with members of his own species. However, just before she can give the bag containing Hydroflax's head and the diamond to them, the shoal proclaims their fanatical worship of King Hydroflax. Despite attempts to hide the bagged head containing the diamond, they are stopped from escaping by Flemming, who had betrayed the pair to Hydroflax's body and had promised Hydroflax’s body an even greater head, the Doctor's and was planning to use River as bait (like River, he too had no idea that the stranger accompanying her was the Doctor himself). Hydroflax's body is then finally reuitied with his head, however sensing that Hydroflax's head is beyond recovery and will die imminently, Hydroflax's body destroys it, leaving only the diamond. Hydroflax's body, along with Flemming & Scratch question River on the whereabouts of the Doctor, but she explains that although she loves the Doctor they are mistaken in thinking that he loves her enough to find himself with her, as she believes the Doctor to be incapable of falling in love. Seeing the steady gaze and mild smirk on the Doctor's face, River comes to the realizeation that she had been with the Doctor all along.

Just as the Doctor reveals his identity, Hydroflax's body prepares to decapitate and upload the Doctor's head. However, a Meteor storm hits the ship. River then reveals that she knew that the ship would be destroyed by a meteor strike and would use this situation as their escape plan, taking the diamond in the process. Hydroflax's body attempts to stop them but The Doctor uses Scratch’s universal bank transfer device to overload it causing the computer controlling the body to be "deleted in a merger".  Together, they crash the ship into the planet Darillium (home to the Singing Towers mentioned by the future River as the place where she spent her final night with the Doctor), surviving the crash by getting in the TARDIS.

During the The Doctor & River's final night together at the newly constructed restaurant on Darillium, it is revealed that Hydroflax body had been recovered from the wreckage of The Harmony and Redemption, now being controlled by Nardole & Ramone who work as staff at the restaurant.


  • He was portrayed by Greg Davies.
  • his general design is similar to the Chaos Space Marines of Games Workshop lore.