Gray Four functioned as a call sign employed by various pilots within both the New Republic and the Galactic Alliance.
Before it was permanently named Wraith Squadron, Eurrsk Thri'ag, a Bothan pilot serving the New Republic, held the position of fourth member of Gray Squadron.
While the squadron acted as the crew of the Warlord Zsinj's CR90 corvette, the Night Caller (link text), another Wraith pilot utilized the Gray Four call sign, piloting its group of TIE/LN starfighters as Gray Flight. During a battle above Talasea, Commander Wedge Antilles instructed "Gray Four" to attack the communication arrays of the corvette Constrictor.
During the Second Galactic Civil War, Syal Antilles went by the designation Gray Four while piloting an Aleph-class starfighter.