Zakar

 was a wealthy Gallifreyan who offered a prize for advances in time technology. (AUDIO: Evolution) He later argued with Romana II about appeasing the outlanders, and wanted parts of Gallifrey. He also said she wasn't the Romana he once knew. He was very well known amongst the Galifreyans. His shuttle was shot down by Leela's township, and took him into custody to trial him for the murder of 237 slaves. He knew that Romana wasn't the original Romana from his universe. Narvin found the proof that Zacker had caused the murder of the slaves, and was promptly arrested by Slyne. (AUDIO: Arbitration)