Thunder Dragon King

The Thunder Dragon King is the main villain of the arc under the same name. He infiltrated the server dimension with only one intention, and that is to rule over everyone. He is planning on doing this by mind controlling every member that is in the dimension.

His appearance is mostly based off of the original "Thunder Dragon" monster, with brownish armor and duel disk.

Introduction
The King was first introduced in the "Thunder Dragon King", and he's a character exclusive to that arc.

The Thunder Dragon King Arc
The crew has found server members either unconscious on the floor, or acting aggressive, mindlessly dueling other people.

While these people were being mind controlled by someone, if their opponents would lose to them, they would become mind controlled as well, acting like some sort of "virus".

The crew later found a server member that seemed different than the rest, and it revealed that the member is indeed the one behind the mind controls. He calls himself the "Thunder Dragon King", but it does not seem like he has an actual name.

After he introduced himself, he blasted the crew with a shock wave that made them fall under his control.

This worked on Mute and Biff, but not Tinkomut and Kaiserman. Because of this, he challenged both of them to a 2 vs 1 duel, which has the dark game rules. After a tricky duel, the Thunder Dragon King was defeated, and since it was a Dark Game, the King's soul left his original body, and escaped to the nearest vessel, which ended up being Simon.