Gandarotethetledrax (Gandar for short) and his partner Cavis were Gallifreyan Celestial Intervention Agency agents recruited from the Patrexes College. They were totally loyal to Lady President Romana III. Gandar was also a fan of the Master, prompting him to model his appearance after the infamous renegade with the goal of being the one to take on and kill the Doctor.
During a confrontation with the Eighth Doctor, Gandar was stabbed in the heart by Margwyn but regenerated as Margwyn was unable to impale his second heart. He was forced to regenerate again shortly after this when he was impaled on a sword, with his new incarnation resembling a hybrid of human and Silurian. His new self was far more peaceful than his previous violent selves, grieving over Cavis's death. (PROSE: The Shadows of Avalon)