Sorcerer (Warhammer 40,000)
Start with a Space Marine Librarian, add some heresy, and you get a Chaos Sorcerer. They are the heavy-duty psykers of the Chaos Space Marines. They feel the Warp overtaking them, and to them, it is a good pain.
For the most part, Sorcerers see themselves as great discoverers of arcane knowledge, studying the Warp from a perspective that the foolish worshipers of the Corpse God deny themselves. They often lead warbands of other Chaos Space Marines, either because they want to learn, too, or to do the fighting while the Sorcerer does the learning.
While they certainly can be scholars or warlords (or both), the dirty secret of the Sorcerers is that they are just as much pawns of the Chaos Gods as everyone else. Magnus the Red (and all of the Thousand Sons) learned this the hard way during the Horus Heresy, when the Rubric of Ahriman turned all non-psyker Thousand Sons into Rubric Marines.
Tzeentch is often considered the patron Chaos God of Sorcerers, as arcane knowledge (and manipulating pawns) is part of his purview. Nurgle and Slaanesh also have Sorcerers within their ranks, though not to the extent as Tzeentch. Khorne, on the other hand, usually hates them (in fact, they cannot take the Mark of Khorne in-game), but he may make an exception for particularly bloodthirsty psykers, like Azariah Kyras.
It is worth noting that while most sorcerers are also psykers, a sorcerer does not have to be a psyker.
Noteworthy Sorcerers
- Ahriman: Maybe the most famous and powerful Chaos Sorcerer of all time, second only to his primarch. Responsible, among other things, of the epic fail/epic win that was the Rubric of Ahriman who turned his legion into the state that it is now, gaining is ass kicked from his legion in the process. Now is searching the Black Library, but failing in doing so. To his credit he gained land each time he tried and now he's getting frighteningly close this time. Some say that he's reconciled with his legions and its members have joined his search.
- SSSSIIIIINNNNNDDDDRRRIIII: Sorcerer of The Alpha Legion. Maybe a Daemon Prince, but got his ass pwned by Gabe so he couldn't properly ascend and died, the sexy-voiced bastard. Currently residing in Abaddon's bionic arm.
- Neroth: A sorcerer of the Black Legion and the nagging wife of Eliphas. Unlike the pansy bitches above who prefer to plot and sit on their asses, Neroth's entire thought process, life motivation, and military strategy amounts to "APPLY WARPFIRE", which tends to divide the opinions of elegan/tg/entlemen on him. Rumors of his being a Khornate Sorcerer are unsubstantiated. Rumors say that he host a barbecue every Sunday in the Vengeful Spirit. Also a sexy-voiced bastard.
- Nemeroth: A sorcerer with his own warband, the Chosen of Nemeroth. A manipulative guy who corrupted a radical Inquisitor into the creation of a warp-fueled power source only to almost ascend to daemonhood and invade a forgeworld in the process. As Sindri, he was killed while ascending, but by one of the very few awesome smurfs. Oddly, he isn't armed with any Force weapon, but with a pair of flesh-engraved lightning claws and terminator armor. His face is fucked up, even compared to Eliphas.