Baltazar

Baltazar was a space pirate who had once been imprisoned on the prison planet Volag-Noc. Initially determined to compress the planet Earth into diamond, an act which would have killed off life on the planet, the Doctor and Martha Jones stopped him. Later, Baltazar went on to search for the lost ship, the Infinite via its data chips, and used the Doctor to track it down. He had a metal bird pet called Caw.

Baltazar is referred to as "Corsair-King of Triton ", although it is unknown whether this means that he had actually seized power on Triton or was merely a pirate who operated near it. The Doctor seemed to favor the former when he refers to him as "The greatest despot that ever, ever lived." Although it should be noted that this could simply be the Tenth Doctor's penchant for hyperbole at work.

Baltazar was also famous for having built his own warship, which he considered the finest ever built, by hand over "countless decades", an accomplishment that The Doctor considered "really cool" moments before he destroyed it with a spoon.

The Doctor referred to him as the "Scourge of the Galaxy". Despite this, Baltazar was notable for having a sense of humor (rare among the Doctor's opponents) and was seen poking fun at Martha and laughing while watching the Doctor awkwardly trying to pilot Caw's offspring, Squawk. (DW: The Infinite Quest)