His identity is still unknown. He led and founded GlobeX corporation but he was defeated twice by SFH forces. First time they thought he was dead was when he exploded with a nuclear missile that he attempted to use to destroy the island full of the toxin, which was developed by the Scientist when he worked for him.
But the leader cloned himself, and attacked the world once again with his mech full of nuclear devices. However, the Scientist betrayed him, and continued working with the Heroes to stop the leader, but only to take his place in the organization. The SFH thought they killed him when Wesley shot him off the mech.
But in SFH3, it is revealed that the Scientist completely took over GlobeX. When the SFH defeated his clone army, it is also revealed GlobeX leader is still alive, and it is probably his clone. He appears in the final cutscene, in a video he sends to the SFH base, saying: Globex, eh....I may be able to help with that.
He probably wants revenge because Scientist betrayed him, so it indicates he will fight for the Heroes in the next game.