That same year, the Earth Outposts guarding the Neutral Zone came under attack by a Romulan Bird-of-Prey – equipped with a new, advanced cloaking device, and powerful plasma-based weaponry – whose crew was on a mission to test the resolve of Earth force after a century of nonexistent contact with Humans. The attack resulted in massive damage and casualties, including the deaths of Hansen's weapons crew. Hansen was subsequently contacted by Captain Kirk aboard the USS Enterprise, who was attempting to intercept the enemy vessel before it could attack again. After giving a report on the attack to Kirk, Hansen was killed when Outpost 4 was destroyed in a final attack by the Romulans. (TOS: "Balance of Terror")
Commander Hansen was played by Garry Walberg.
This character's name is spelled "Hansen" in on-screen credits, but was consistently spelled "Hanson" throughout the revised final draft script of "Balance of Terror" (dated 18 July 1966), wherein the stage directions indicated he was to have a "singed, bloodied look."
Though described as a "commander" in dialogue, Hansen's uniform bore no rank insignia.
In a deleted scene from the shooting script (Scene 46, p. 17), Hansen wanted the Enterprise to warn Earth that either traitors or Romulan spies had stolen starship designs and used them to build the Bird-of-Prey.  The scene had actually been shot, but was excised from the episode as aired. . The remarks of spies was however said by Naviagor Stilles