Fillian McCarthy was a thief who, just like his older sister Gillian, learned the ways of the streets in order to survive. Unlike his sister, Fillan chose to steal for a living, while his sister became a seductress.
As Gillian manipulated her way up the social ladder, Fillan broke ties with her and came into contact with the Assassins, after she had sided with the Templars. As a young man and able to take care of himself, his only loyalties were to his next meal and in helping the Brotherhood.
In 2012, his genetic memories were used as an Animi Avatar by the entertainment branch of the Templar company Abstergo Industries, to influence the general public via the Animus games console, under the title of the Robber.
- In his entry in Abstergo Story, which functions as the database for Assassin's Creed III multiplayer, Fillian's name is mentioned twice, specifically in the line "Like his older sister, Gillian, (C'mon Gillian and Fillan... :S) Fillian McCarthy learned everything he knew from the streets." Since his name only appears twice, it is unclear which one is the typographical error. However, since he is introduced as "Fillian McCarthy", and the name is meant to parallel that of Gillian, this article assumes that Fillian is the correct name.