Takeshi Todo
A lonely, rich classmate of Naoto and his friends. Alone and having no friends himself, Todo enjoys making monsters on a PC Game known as "The Castle of Torture". He was put under Kahn Digifer's control to make monsters, which Kahn Digifer then brings to "life" in the computer world. Takeshi's motivation for making a monster varies each episode. He makes their as a means of getting revenge on a mistfortune, petty grudges, or punishing humanity. Takeshi also develops an unhealthy crush on Yuka, having some of his creations targeted her specifically. He was eventually freed from his control and helps Naoto and his friends find a way to defeat Kahn Digifer.

Dark Lord Kahn Digifer
The main villain. A Legendary 'Devil' of the Computer World that wishes to wreak havoc on the Human World. He joins with Takeshi Todo, putting Todo under mind control to create monsters which he brings to life in order for them to attack the Computer World. He later upgraded himself into Gigantic Kahn Digifer for his final battle with Gridman, destroying Gridman's Helper Vehicles and overwhelming him. Kahn Digifer was ultimately destroyed by the Grid Hyper Beam.