Agent X

Agent X is a mysterious operative working for Doctor Ivo Robotnik. Robotnik believed that Agent X was Johnny Lightfoot, a member of the Freedom Fighters who had turned traitor, but he was really an alien named Shayde from the Shadow Dimension, who had replaced the real Johnny months earlier. As Agent X, he wore a hooded cloak to hide his identity.

History
The being known as Agent X was created when a temporary split in time and space allowed the creature called Shayde to make contact with Mobius. By touching Johnny, Shayde absorbed his appearance and identity in order to survive on Mobius. As "Johnny", Shayde approached Doctor Robotnik, offering to betray the Freedom Fighters and work for Robotnik instead.

Agent X's first mission was to plant the Doom Seed under the Metropolis Zone, so that it would eventually grow and cover the whole city with weeds. However, Agent X was spotted by Sonic the Hedgehog and narrowly escaped by teleporting away. Agent X was later sent to Trituna to offer Zone Leader Sharka Khan a serum that would grant him and his citizens the ability to breathe on land, in exchange for defeating Sonic.

As Johnny, Agent X lured Tails to the Sun Valley Zone, which had been wreathed in fog by Windy Wallis's weather machine. Disguising himself as Agent X once more, he attempted to use the fog as cover to ambush and shoot Tails, but Tails gained the upper hand when he used his twin tails to blow away the fog and then destroyed Wallis' fog machine. Wallis escaped, while Agent X removed his clothes and presented himself as Johnny Lightfoot, claiming to have landed far away and to have only just arrived on the scene.

When Robotnik disappeared after a defeat on the Floating Island, Sonic gathered the Freedom Fighters to storm Robotnik's base on Flickies' Island to rid the island of Robotnik's influence. Agent X, present at the meeting as Johnny, volunteered to stay and guard the Emerald Hill Zone but teleported himself to Flickies' Island as soon as the others had left. There, he managed to gain control of possibly every Badnik on the planet (albeit the older models) and sent them to intercept the invading heroes. The Badniks severely outnumbered Sonic and the gang, capturing them one by one, and brought the gang as prisoners to Flickies' Island. Agent X still did not reveal his identity until seemingly vaporising Sonic with a bulky machine. With the hedgehog out of the way, Agent X revealed himself to be Shayde, but was quickly captured by Shortfuse the Cybernik. Tekno the Canary reversed Agent X's machine, which was really a matter transporter, to bring both Sonic and the real Johnny Lightfoot back from the Shadow Dimension. Agent X tried to shoot Johnny, only to hit the matter transporter, causing the entire base to explode. However, before this happened, the real Johnny grabbed Agent X, and the contact caused Agent X to change back into a shadow and return to his own (self-destructing) dimension.