The Master
The Master is a renegade Time Lord with a notable lust for power. The Master is a rival and frequent adversary of the Doctor.
Attributes
As a Time Lord, the Master has an unnaturally long life expectancy. At one point he had already used up the limited number of "regenerations" that Time Lords can undergo to rejuvenate their bodies and was physically decaying, but he managed to somehow possess the body of another person to renew himself.
The Master has a genius-level intellect and possesses detailed knowledge of multiple scientific and technological fields. He is also well-traveled and able to fend for himself on nearly any civilized planet.
Paraphernalia
At some points in his history, the Master possesses a TARDIS that enableds him to travel through time and space. Its chameleon circuit appears to be damaged, as it always seemed to resemble some variation of a grandfather clock. This may just be a personal preference as in Castrovalva it was seen in the form of a fireplace.
The Master frequently carries a weapon that kills by molecular compression, turning the victim into a miniature, doll-like corpse. He recently constructed a "laser screwdriver" with a variety of uses.