Mokujin was introduced in Tekken 3, and returned for all subsequent games (with the exception of Tekken 4).
Mokujin has no fighting style of his own. Instead, he chooses the fighting style of another character that is competing in the current tournament and uses it. Mokujin changes fighting styles after every round, although it will occasionally use the same fighting style two rounds in a row. In addition to this, Mokujin will mimic the pre-fight and win animations of whomever it is mimicking, but it will not make any sounds during them, because of its inability to speak.
Mokujin was the first fighter in the series with mimicry, with many other fighters mimicing fighting styles after that. Mokujin is the wooden version of Tetsujin, whose only playable appearance thus far is in Tekken Tag Tournament.
Mokujin's complete background aside from coming from a thousand year old oak, called out to fight supernatural evil, is completely unknown. Mokujin however confirmed that he had been around for hundreds of years and had known many abnormal powers including those belonging to Jun Kazama, and remembering who Azazel was before it could say it's title as the rectifier. Mokujin often surprises others by talking to them through telepathy (as revealed in the Scenario Campaign) as well as having his own form of communication by making sounds of something knocking on wood. He is often surprised at how humanity has always acted in times of crisis. He wonders at how humans could cause many major conflicts, but still had the power to mend things. He often judges people based on the type of spirit they give off, and he reveals that he can actually "sense" things through aura. The same cannot be said to those who generally meet him as they all think that Mokujin is nothing more than an abnormal training dummy except for a few. It is believed in past folklore that if the world would be on the brink of collapse due to the presence of a supernatural being, then Mokujin would appear. The only ones who are confirmed to have known this were Wang, Feng and his master, all of which revere Mokujin as something of legend. Despite being called legendary, Mokujin always wonders whether or not he is actually needed due to him being labelled as something abnormal. He does however believe that if there are people who are still fighting for a just cause and have a capable aura and spirit, then he still has purpose in the world
His title in the original trilogy is Wooden Person.