Claus Warwick (クラウス・ウォリック, Kurausu Uorikku) is Leila Malcal's aide-de-camp in the E.U. military's Special Forces Unit "W-0." It is implied that he has a child but is in bad relations with his wife. Later he was revealed to be a Britannian spy all along as he has been shown transmitting information to the Britannians. He also appears to be an alcoholic, drinking out of his flask or pouring alcohol into his other drinks, but this may be a front to divert suspicion from himself.
However, Leila knew of his betrayal was due to supporting his daughter and never turned him in. Due to this and his attachment to the rest of the W-0, he defended Leila against the St. Michael Knights giving up his own attempt to have asylum in Britannia.
He also revealed to Lelia of General Gene Smilas' betrayal of her.