The Guildmaster is the founder of the unnamed Kidnapping Guild Suki is part of.
He is first encountered by Suki during her attempted escape from the lair, blocking her path along with the rest of the guild. Impressed by her, he offers her a choice; accept a place in the guild and work for him, in exchange for assistance in tracking down Cherisa, or be returned to her cell on a more permanent basis. She accepts and joins the guild, and from this point forward, he acts as her boss, providing mission briefings to her. On his orders, Suki kidnaps women from the nearby Huston Village (Mission) and Velis Manor (Mission), assists mages and tomb robbers with their respective problems, and breaks a blockade on the guild in a northern village.
Feeling that she has contributed enough, the Guildmaster provides his promised assistance to Suki, sending her by ship to the Dark Hills, though in exchange for her services to the trading company which owns the ship, as a bodyguard. Unfortunately, she fails in this task, much to his distaste. He chooses to send her instead by carriage, and from this point forward, he is uninterested in conversing with Suki at all, feeling that their business is concluded.
He appears in the epilogue, speaking with Leroy and other members of the kidnapping guild. They discuss how Suki has coerced the kidnapping guild into releasing their captives and relocating, and the Guildmaster reveals that his original hope was that Suki would abandon her quest for vengeance against Cherisa and become a permanent member of the guild; his gamble did not pay off. He finally remarks that with this, any cooperation between Suki and the Guild is over, and thus Suki is a fair target for the guild in future.
The Guildmaster is ruthless and businesslike, but is not above issuing compliments to well-performing subordinates. Though he is never seen in combat, it is commented upon by Francis that he is reasonably strong, though not the strongest member of the guild - he rules because of his ability to manage the guild effectively.
The Guildmaster has little patience for failure, becoming very angry with Suki for her failure to protect the merchant ship from the pirates, despite the overwhelming odds stacked against her. This is also implied from the ending of the Pirate Bay mission if Suki surrenders to the pirates in Whitebone Cove or fails to escape. After Suki's initial capture at the hands of Alyssa, a pirate suggests that Suki would be ransomed rather than being sold if her boss were willing to pay for her, but if Suki is captured again after her escape, she will instead be sold as a slave, indicating that the Guildmaster does not pay the ransom.