Fraternal Order of the Raven

The Fraternal Order of the Raven are an antagonist faction in the video-game Bioshock - Infinite, due to the game being fairly new this article will contain minor to mid-spoilers.

The Fraternal Order of the Raven are a xenophobic group clearly inspired by the Ku Klux Klan and a secret society, some of its members have the ability to summon murderous crows (which is available to the main protagonist as well, as a Vigor).

Information
(taken from Bioshock wiki - will be edited as appropriate, all credit to original author(s) )

The Fraternal Order of the Raven is a Founders-affiliated organization in Columbia concerned with maintaining the city's "racial purity". In contrast to Columbia's holy symbols of the sword, the key, and the scroll, members of the Order of the Raven use the symbols of the sword, the raven, and the coffin. Their symbol is that of a stylized eye with five swords crossing behind it and a banner which reads "Audemus Patria Nostra Defendere."

The group worships John Wilkes Booth as a saint for assassinating Abraham Lincoln, "the Emancipator" or "the Apostate" (a term Comstock often uses in reference to the same), whom they view as "evil" for abolishing slavery. Members of the Order cloak themselves in hoods and robes, with lesser members wearing blue and leaders wearing black. The Order believes that Columbia's racist ideals make it and its citizens superior to the rest of the world, and seek to enforce a doctrine of racial purity.

The most prominent members of the Order are the Crows: fearsome, coffin-bearing enemies whose powers mirror that of the Order's namesake. They count among the elite forces of the Founders, and are occasionally sent to kill Booker DeWitt.

Booker discovers the Order's headquarters in Comstock Center on his journey to Monument Island. The building's interior is squalid, with debris littering the floor, the lighting system dim and continually flickering, cloth curtains and tapestries torn and threadbare, and raven feces scattered throughout. Platters of rotten food are ubiquitous, especially in the dining hall, and attract many flies and ravens. Other features include a large statue of John Wilkes Booth in the foyer, a lounge and bar, a reading room, a large ceremony hall, a dungeon cell hidden behind a bookcase, and a marsh-like indoor garden where victims are kept in golden cages hanging from trees and tortured. While traversing the building, Booker clashes with several Order members before battling their leader, a Crow.