Varkladian Knight

s were alien beings briefly encountered by Berthold Schwarz through a portal in the 15th century.

Biology
Varkladian Knights appeared as very tall humanoid beings entirely clad in bright gold traditional knight's armour with an equally gold gun by their hip.

History
While conducting an alchemy experiment in the 15th century, a young Berthold Schwarz accidentally summoned a portal that led to a Varkladian Knight. It offered him its gun but he chose to shoot and kill it. The Thirteenth Doctor and Yasmin Khan, witnessing the events, eventually learnt that its dying scream was actually a blood curse, leaving Schwarz immortal unless he was shot by the last gun on Earth. The curse was later broken by an older Schwarz in 1605 being convinced by his far future self not to destroy the Houses of Parliament.

By the Thirteenth Doctor's time, Varkladian Knights were viewed as nothing more than a myth. (PROSE: Black Powder)