|Appears in||The Keys of Krodacia, Dead in the Desert, Battle of the Brains|
|Shots to defeat||immortal|
In The Keys of Krodacia he is introduced as a member of the Vorticon Special Forces sent to Krodacia to help Commander Keen find the keys needed to gain access to the Universal Toaster Canon. Keen is initially reluctant to have Barker around, advising him to stay out of his way. Lt. Barker can be found in two levels: the Mansion, where he reveals to Keen that a swim coin can be obtained in the level Monk's House, and in Mushroom Forest where he is unable to jump out of a pit because it is too dark (a nod to the Vorticon's inability to jump in the dark in Keen 2).
In Dead in the Desert Lt. Barker makes an appearance in the end sequence where he (and Keen's other friends) are in command of the Bean-with-Bacon Megarocket and have come to rescue Commander Keen and return his ship to him.
In Battle of the Brains Lt. Barker plays a key role in establishing the plan to stop Mortimer McMire and appears in the level Elevator Access Station to warn Keen about the terrifying Krodacian Overlords.
Lt. Barker is also one of the 8 playable characters in NetKeen.