Hydroflax

His Infinite Majesty, King Hydroflax of the Final Cluster, has a fearsome reputation throughout the galaxy. Warrior, dictator and not all that bright, this villain has been responsible for all manner of terrible incidents across the cosmos. Yet even by his standards, the Butcher of the Bone Meadows’ raid on the Halassi vaults was as daring as it was stupid. In the ensuing fire fight, the entire vault blew up in his face, with the result that the universe’s most valuable diamond – the Halassi Androvar – became lodged in Hydroflax’s head! It was in the hopes of extracting this diamond that River Song married Hydroflax – technically she married the diamond – and summoned a surgeon to remove it. Unknown even to River, that surgeon naturally turned out to be the Doctor!

When necessary, Hydroflax was capable of completely detaching his organic head from his mechanical body, with both parts able to operate independently. Hydroflax’s body was also able to upload the heads of other lifeforms when information was required, a trick he used twice on River Song’s associates Nardole and Ramone. Once Hydroflax’s body had determined that the organic head was too badly damaged to be reintegrated, the Doctor connected the body to the galactic stock market and overloaded his software, allowing him and River to escape. Retrieving the body from the wreckage of the starliner on Darillium, the Doctor reprogrammed him so that - with Ramone and Nardole’s heads still attached – he could wait tables in a restaurant overlooking the Singing Towers!