Adwin Kosan is the head of the Regents. A very mysterious man, he has ultimate authority on matters regarding Warehouse 13.
Adwin Kosan made his first appearance in Vendetta. After the incident with H.G. Wells and the Minoan Trident, Mr. Kosan appeared to take her away to be judged for her crimes. The events of "The 40th Floor" suggest that, for his own safety, Mr. Kosan sleeps in different locations almost every night, and has his own personal security force at all times. This would imply that he cannot simultaneously hold down a 'normal' cover job, as is typical for most Regents.
Mr. Kosan, in a manner similar to Benedict Valda, does not brook direct challenges to his authority, or react well to what he feels to be insubordination. He does, however, appear to have considerable empathy for the difficulty of the Warehouse Agents' job, and shows no signs of holding a grudge. He is far less inclined to punish Artie for Leena's death that Artie himself is. He is the only Regent whose position in the hierarchy is clearly above that of Jane Lattimer.