Ambrose is the ultimate arch enemy of The Doctor. He first appeared alongside the Ainsley Master in Series 12, who he later left for dead in Nazi Germany after stealing his sonic spatula and TARDIS.
Ambrose is the only product of a Kaled/Timelord breeding program. It was theorized by many civilizations that Ambrose used the Ainsley Master's TARDIS to travel back in time and create the emotion of hatred.
He is humanoid in appearance, although due to his genetic make up, has no mouth, meaning he communicates via an electronic speaking system or through angry muffles.
The Jazz Doctor encountered Ambrose for the first time when he was avoiding 'the announcement'.