Once a childhood friend, the Master is a rival Time Lord who is the direct equal and opposite of the Doctor. The Master has endlessly attempted and failed in conquering the universe, being prevented so by the Doctor. During his travels, the Master has gained considerable knowledge and ways to defend himself. One of his well known traits is to hypnotize his victims so they succumb to his will. In his many attempts to conquer the galaxy or just rule one planet, he has been helped by another alien race such as the Axons, the Autons, the Ogrons, the Daleks and the Sea Devils.
It is also currently rumored that the Master is on his final regeneration and is looking for a way to give himself more lives.
Master Of The Daleks