In "The Conjugal Conjecture", the Colonel showed up at Howard's door and Raj lied that he wasn't there. Howard then calls him up and they agree to a meeting at Caltech, but the Colonel won't discuss what he wants.
In "The Military Miniaturization", the guys meet with the Colonel. He won't tell them what their guidance system will be used for because it's "none of their business". Sheldon tells him that the project of making the guidance system smaller can be done in two months.
In "The Dependence Transcendence", the guys are worried about meeting their two month deadline to finish their project and go to visit the Colonel. After a brief moment of tension, he says that he is fine with two years since they are not the first government contractor to not make their deadline.
He reappeared in "The Locomotion Reverberation", where Leonard and Howard have told and shown him that they've completed the gyroscope he wanted from them. Unfortunately, the colonel sees the theory Sheldon created for a smaller one, he wants them to make that one. Despite the fact that Howard and Leonard pointed out that it was only a theory and they can't do it, the colonel hears their pleas, but ignores them and insists that they make the smaller one Sheldon hypothesized, much to their chagrin.
He reappeared in "The Gyroscopic Collapse". After cleaning out the classified lab of all the contents, Leonard, Howard and Sheldon skyped with the Colonel inquiring why everything was gone. Of course he would not tell them anything, except to confirm that is was he that removed everything. The guys were devastated, Sheldon taking it particularly hard.
- S10E01: The Conjugal Conjecture
- S10E02: The Military Miniaturization
- S10E03: The Dependence Transcendence
- S10E15: The Locomotion Reverberation
- S10E23: The Gyroscopic Collapse
- Like Howard, Colonel Williams is a MIT educated engineer.
- He initially thought the Death Star was from Star Trek until Sheldon corrected him.
- In "The Locomotion Reverberation", Colonel Williams is shown to be a very stubborn man, as he forces Leonard and Howard to follow through with Sheldon's theory for a smaller gyroscope, in spite of the fact that they already designed the one he had wanted, they don't want to do so, and that making a smaller gyroscope is nearly impossible.
- In The Gyroscopic Collapse it is shown how ungrateful he can really be, as he took the guys project from them without even consulting them.
- While it has never been mentioned that Colonel Williams is married, he obviously is, as he is seen wearing a ring.