Tony Stark created android X-4 under the influence of Nick Fury to locate a traitor within SHEILD, which Fury believed was Steve Rogers.
Android X-4 was created and designed by Stan Lee and artist Gene Colon.
Android X-4 made only one appearance within Captain America #127 and would never be seen in comics again.
Major Story Arcs
Nick Fury became suspicious and believed that there was a traitor among his organization, this caused him to narrow his conclusion to Captain America seeing how the Avenger could easily gain access within SHIELD without any security clearance. Yet Nick Fury realized that this claim might be a wild accusation and force Nick Fury to find a way to test Captain America’s loyalty and possibly find the real traitor is Captain America was innocent. Having Tony Stark design a robot to test against Captain America, Stark designed Android X-4. Powered by radiation for specific purposes, Android X-4 was designed to perfectly hold himself in battle against Captain America as the android had matching strength and reflexes.
Requesting Captain America to a SHEILD base in New York, Nick Fury tricked and forced the Avenger into fighting against the android. Convinced that Captain America was innocent of Fury’s suspicion, Fury tried to shutdown the android but realized that somebody else was controlling it. Anticipating this, Fury had Sharon Carter track the radiation signal with a Geiger Meter and located the true traitor within SHEILD, which was the scientist known as Dr Ralph Ryder. With Ryder captured, Fury falsely admitted that he suspected Ryder as the traitor and was using Captain America as a decoy.
Powers and Abilities
Android X-4 is an android that is specifically controlled by another through remote means. The android was specifically designed with flaws and powered by radiation for the purposes of tracking another signal incase the android was controlled by another. Aside from it’s robotic and electronic feature, the android has superhuman strength and reflexes with steel-hard skin.