Jon Irenicus

***Warning, Spoilers for " Baldur's Gate II:  Shadows of Amn" below***
 
Jon Irenicus is the main antagonist of Baldur's Gate 2: Shadows of Amn and is responsible for your capture at the beginning of the game.  You first meet the powerful mage during the games prologue, starting with your imprisonment some time after the events of the Iron crisis as depicted during the previous game.  Irenicus speaks civilly to you from the beginning, informing of his plans to unlock your latent abilities as a child of Bhaal.  A plot soon foiled as a guild war spills over into his dungeon; warring factions batteling for superiority over the streets of Amn.
 
During the chaos, and your subsequent escape through the labyrinth of his lair, you're given an unwelcome glimpse into the fractured psyche of this tragic figure.  The forgotten clones of a love long-lost float forgotten inside the dark containers of their conception.  The many of them hideous monstrosities or lifeless beasts, a few linger on in the shadows awaiting their "master's" call...

Irenicus has a lust for power - such an insatiable urge that he was kicked out of his city of birth and banished along with his half-sister Bodhi. Both of them are elves, although each go to different lengths to disguise it - Bodhi adopts vampirism and Jon either removes his ears or simply keeps his skull cap on at all times (it's never made clear). His banishment has done nothing to satiate his urges, only fuel his desire for revenge, and as the child of Bhaal you're the prime target for him to build his power.

His plan is carried through to fruition midway through the game where he literally steals your soul and augments his already formidable magic powers. He plans on using the power to incite a war between the Drow (dark elves) and Elves, and use the resulting chaos to steal the essence from the elven Tree of Life, becoming a god in the process.

After foiled in his plans a final time, Irenicus is swarmed by demons in hell and torn to pieces.

Jon Irenicus is voiced in a grand manner by David Warner, a theatre actor who also played Morpheus in the original Fallout.