Colonel Blintz, after his disfiguring head injury
Colonel Blintz was an ex-officer of the Green Nation. Blintz was in charge of a Green-held region until he was injured in the line of duty when he was shot in the head; the injury was described as a "massive, disfiguring head wound." Afterwards, he disappeared, only to resurface later as a member of the Tan Republic, taking his soldiers with him. The soldiers that wouldn't join him were melted down for scrap.
In Army Men: RTS, Blintz is intent on dominating the Real World and is using the Green Army's own tactics against them. He is defeated and is a sap about it until Sergeant Hawk peeled off the paint after beating Blintz up. It's possible that he isn't part of the Tan army but of a different faction that he created with his troops.