Eubulon

Eubulon, known as the "Advent Master", is the creator of the Kamen Riders. He once worked with General Xaviax to create a machine to transport a large amount of people from other planets. He had a change of heart in this plan and created the Kamen Riders to destroy the machine. He created a Kamen Rider just for himself and has the power to change the DNA sequence of the Rider Decks so anyone can use it. He fought Xaviax to a draw and ended up being found in Roswell on Earth. He warned the No-men of Xaviax upon his arrival but was injured badly and was unable to tell them anything else. 60 Years Later, Len was brought in to reactivate Eubulon. Len had informed him about Adam's betrayal. With Xaviax on the move, he reassigns the Siren deck to Maya as she helps Len stall Xaviax as Eubulon goes to retrieve the Riders in the Advent Void. He manages to bring the Ventaran Torque, Strike and Axe (named Chance, Price and Hunt respectively) as he and Len expain their current situation to them. He gives him a device that will upload a virus in Xaviax's transportation devices as they will need some of them to retreve the people of Ventara.

Eubulon, being the creator of the Kamen Riders, has the ability to manipulate the rider's arsenal. He can change the DNA lock each deck has and reassign it to other people if necessary. He also has the key to the Advent Void, which he created as a fail safe to prevent any Rider from getting killed in action. While the key was damaged with his fight against Xaviax, it still functions well thus making any future vents a non-issue, but as it is damaged, he can only use it for a limited amount of time before he must repair it. He also has his own rider gear with which he can use to fight with. With his reappearance, the war against Xaviax has changed from a fight for survival to a fight against time.

Eubulon is portrayed by Mark Dacascos.