Very little is truly known about the organisation who call themselves the Shadow. Believed to have been founded sometime during the reign of the Empire, most likely as an illicit offspring of the IIA. The Shadow are an organisation of assassins, not simply devoted to profit but rather to the act of murder itself. Unfortunately, due to the secretive nature required or at least expected of professional assassins, very little is known of the membership or hierarchy of the Shadow. Whilst estimates would place this organisation as having roughly 100 members globally, what the Shadow lack in quantity they make up for with ruthlessness.
Recognised as existing and responsible by their trademark "calling card" being left at the scene of a death, it is worth noting that whilst being known colloquially as assassins, there seems to be no evidence connecting the disconnected murders for which they claim responsibility with any contracts. Due to the generally disconnected nature of these murders, and the apparant lack of requirement for a contract, any and all may be targeted, thus furthering the assumption that the Shadow feel a distinct connection to the act of killing moreso than the act of assassination.
Whilst very few murders committed by individuals or groups that can be linked directly to the organisation are available for publishing due to various requirements for clearance or security, it is worth noting that the very loose methods undertaken by the organisation with regards to obtaining a "clean kill", combined with the leaving of a calling card claiming responsibility, gave rise to a number of copycat murderers attempting to shift blame for their crimes onto the Shadow. These criminals are, perhaps, the single outlier to the Shadow's otherwise uncorrelated murders, as each individual who would later be discovered and named as the true perpetrator of such a copycat murder had to be named posthumously, as some time previous they were discovered with a calling card from the Shadow.