Third Doctor

The Third Doctor, who was exiled by the Time Lords to Earth, in the twentieth century time zone, for a significant period of his life, was a distinguished man of high class and gadgetry, often tinkering away and privy with machines. He also liked to share his wisdom with those who had open minds, but his patience would quickly dissolve if something annoyed him. Those who got on his good side soon found him to be a friendly fellow, while those who were against him soon found that this gentleman could actually get physical and hold his own in a fight.

The technological limits of the time period, and the constraints of his exile, often made him frustrated and bitter. However, he retained his endearing compassion toward his human companions, and he finally began to gain some mastery over his TARDIS as he dissected its inner-workings while it was rendered inoperable as the exile gave him the opportunity to learn more about his ship than he ever had before since he was no longer constantly on the move from his people.

This incarnation of the Doctor worked for UNIT as their scientific advisor, and remained in their service after his exile was ended. Unlike his earlier incarnations, he was quite willing to engage others physically, and cut a more dashing figure.

His foremost enemy was a fellow Time Lord, the Master. Although appalled by the disregard for life inherent in the Master's schemes, the Doctor treated their relationship as somewhat of a friendly rivalry, even enjoying their battle of wits. The Master reflected an equally casual attitude back at him. The Doctor also held out hope that he could rehabilitate the Master, whom he had once considered a friend. Though the Master sometimes teamed up with the Doctor to deal with foes who threatened them, he always bent to dark and malicious desires, which kept their mutual antagonism alive. Indeed, when they did work together, they showed a mutual respect of each other's abilities. More than once, the Master did offer the Doctor the opportunity to share his power, but the Doctor always refused.

In the field, the Doctor was aided by Sergeant John Benton, Captain Mike Yates, and Brigadier Alistair Gordon Lethbridge-Stewart. The Doctor often took exception to the Brigadier's military approach, just as the Brigadier was frequently irritated by the Doctor's air of superiority and seeming disregard for authority. Despite this, the two men ultimately developed an easy mutual trust and strong friendship.

He was initially assisted in the laboratory by Dr Elizabeth Shaw. A capable scientist in her own right, she eventually left to pursue her own work, and the Doctor was given a new assistant, Jo Grant. She was bubblier and had less scientific training, but the Doctor found her a most useful companion in his adventures during and after his exile. They developed a great fondness for each other. Jo left UNIT to marry scientist Clifford Jones.

Eventually thereafter, the Doctor was joined by inquisitive newswoman Sarah Jane Smith. Her journalistic skills and curiosity proved both useful and occasionally hazardous in their travels together.

The Doctor eventually regenerated into a younger body after being exposed to large amounts of radiation during his efforts to stop the Eight Legs of Metebelis III, the price of correcting a mistake he had made in the past.