Commander Mezer Juul was the supreme leader of the Free Fleet around 0 A.E. He offered the Human inmates of Callisto the opportunity to enlist in the Free Fleet after seeing their battle prowess against the Vendal and eventually appointed Maddox Khan as Captain of the Omega Company, an elite division of Human soldiers. Sergeant Kemran James's accounts imply that Juul is a rather militaristic and ruthless individual, selling other species as livestock or worse, exterminating whole civilizations.
He died in 30 A.E. when his flagship was blown up by the Bushraki in the Bushraki War.