Jacques de Aldersberg is the Grand Master of the Order of the Flaming Rose and the true main antagonist of the videogame The Witcher. He founded the Order upon remnants of the Order of the White Rose, but has taken its underlying philosophy in a radical and uncompromising direction.
Jacques de Aldersberg is a fanatical follower of the Cult of Eternal Fire, wielding his innate "source" powers through sheer force of will (having had no formal training). He aims to overthrow King Foltest, bring about a new age and destroy all non-humans, whom he views (at best) as relics of the past. He ordered Count Roderick de Wett to curse Foltest's daughter Adda again to weaken his position.
Using stolen witchers' secrets, and with the aid of the Salamandra organization, Jacques has created mutant soldiers to uphold the increasingly twisted ideals he espouses. It becomes clear that he will stop at nothing to achieve his goals. Before joining the Order, it is rumored that Jacques was a vagrant fueled only by his hatred of non-humans.
The Witcher 2: Assassin of Kings
The Witcher 3: Wild Hunt