General Thorn was a planned general that was cut from the final release of Generals. He was envisioned as the American Special Forces general.
Interestingly, Thorn is the only one out of the original three American generals lacking an analogous counterpart in Zero Hour. Griffon is obviously replaced by Malcolm Granger as the Air Force General, with Ta Hun Kwai replacing Bradley as the Tank General (albeit as a Chinese general instead).
Much like Bradley, Thorn's appearance also may have been depicted in unused cameo textures within the game files.
Thorn, much like fellow generals Griffon and Bradley, will become playable in the non-canon modification Rise of the Reds.