The Elite Hunting club are the main antagonists of the horror series "Hostel" and although they are not often faced in person they play a pivotal role in most (if not all) of the films - the term comes from a widely believed conspiracy theory/urban legend that their are highly active "snuff film" societies that use the internet to maximize their business: as of yet not such society has ever been found.
In the fictional setting of Hostel, however, Elite Hunting are very much active and a real threat, especially to backpacking tourists and have clients from across the world who will pay the company great amounts of money in order to have them kidnap a victim for use in ritualistic killings.
Elite Hunting prize themselves in being loyal to their customers and see murder as simply part of their business, they supply each client with elaborate weapons and a personal room by which to torture their victim and act out any fantasy they may desire: the only rule is that the client must go through with killing the victim.
Elite Hunting is arguably one of the most powerful and well-organized criminal organizations in the world with international support and a hidden underground society of thugs, madmen and trained paramilitary servants by which to enforce their will - though like all criminals they are extremely careful not to alert authorities to their behavior.
Elite Hunting is claimed to be especially active in some of the poorer states of Europe (such as those found in the former Soviet Union) - employing brutal tactics, even by criminal standards (as was seen in one movie when an Elite Hunting agent shot dead a member of a child gang).
As stated before unlike similiar trap-based killers such as Jigsaw Elite Hunting were not motivated out of a sense of vigilantism but rather profit - which arguably made them a far more immoral threat.
As is shown in Hostel: Part II all members of Elite Hunting have a tattoo which identitifies them as members of the society, though presumably this information is only known to members of Elite Hunting.