Dr. Madd has been recognized as one of the more notable Grey Nation soldiers in the Army Men series. It is implied he is behind the creation of Zombies, as he is referenced in the Graveyard level of Army Men: Sarge's Heroes 2. and also created the Anti-Plastification Serum. He is allied with the Tan Republic. His castle and/or name is reference on a lunchbox in one of the levels in Army Men: Sarge's Heroes 2.