Doctor Who - The Master.

The Master — originally called Koschei and known by many other temporary aliases — was a renegade Time Lord and the Doctor's arch-nemesis.

Although they were originally boyhood friends, one of the Master's primary goals was to destroy the Doctor and Earth while acting on a number of schemes, both petty and gross.

The Master - First incarnation.

The Master was referred to as a "jackanapes" and an "unimaginative plodder" by the Third Doctor, the "quintessence of evil" by the Fourth Doctor, "one of the most evil and corrupt beings [the] Time Lord race [had] ever produced" and that his "crimes [were] without number and [his] villainy without end" by High Council President Borusa, "pure evil" by the Eighth Doctor, "stone-cold brilliant" by the Tenth Doctor, and "the Time Lords' most infamous child" by Time Lord founder Rassilon.

The Master - 'Last' incarnation.

It was eventually discovered that the Master's diabolical madness was partially the result of a genuine malady in the form of a never-ending drumming sound that had been retroactively implanted inside his head by the Time Lords on the last day of the Last Great Time War to further their own goals.

Figures by Black Tree and Heresy.