The Colonel is the special forces leader of the Peacebuilding Forces fighting back against the rule of Artemis. He is a cynical and cold-hearted man. He is willing to make sacrifices to carry out his missions.
The Colonel's given name was shown as 'David' upon the character's reveal in February 2022. However, this name had been removed from the official website by March 2022.
(Source: Black Rock Shooter Wiki)