Gate

Gate is one scientist that found a piece of Zero in the remains of Eluria, destroyed in Mega Man X5. He was able to understand part of it, but he turned into one Maverick and created the Nightmare virus, the Zero Nightmare, and High Max. He also ressurected Sigma. Before turning into a Maverick, he was a scientist friend of Alia that created many strong Reploids, but as he frequently desobeys his superiors, he was fired. Gate and eight of his most strong creations appears in Mega Man X6.