Ajax is a Hero that helped fight the Rikti during the Rikti War. He is the only known survivor of the Omega Team, who was caught in a Rikti stasis ray before he was able to run through the portal. Considered to be utterly invulnerable, Ajax was able to survive the blast that occurred when the Omega Team destroyed the portal to the Rikti Homeworld.
Ajax was originally the only known surviving member of the Omega Team. His guilt drove him into years of depression until the Omega Team Time Capsule was opened. It was revealed that the current Ajax was nothing but a thug who killed the original Ajax. Now, Ajax seeks to redeem himself by cleansing the Rogue Isles of all villains within it.
"Ajax" is a name shared by two heroes. Both were considered to be utterly invulnerable.
The first Ajax was shot and killed by a criminal named Ralph Valetti on an outlying island near Talos Island fifteen years ago. He is buried in an unmarked grave. How his invulnerability failed him and he was killed by a standard firearm is a mystery.
The second Ajax is Ralph Valetti, the man who killed the first Ajax. As Ajax died, his powers transferred to Valetti. Valetti took Ajax's costume and identity and continued the heroic career of Ajax. Ajax II was part of Hero 1's Omega Team, but was able to survive the blast that occurred when the Omega Team destroyed the portal to the Rikti Homeworld after being trapped in a Rikti stasis ray. He was the only known survivor of Omega Team until Glacia and Infernia managed to return from the Rikti Homeworld several years later.
In the hero acceptance of the Malta Gunslinger Action Figure Mission Tip, it is revealed in a Longbow file that Ajax spent the years between the Rikti War and the opening of the Time Capsule trying to drink himself into a stupor. Unfortunately, his invulnerability made getting drunk impossible for him.
The nature of Ajax's powers is unknown. The way the original Ajax received them, and the method of transfer to Ralph Valetti is a mystery. What is certain is that they make him impervious to any standard form of attack.
In Dean MacArthur's story arc, MacArthur theorizes that the invulnerability has worn off. It has not. However, Ajax can be made vulnerable by powerful psionic blasts. Ajax also mentions that it is his "fate" to return, and that the vulnerability is temporary. He claims to be immortal and unkillable.
During the mission Ajax and Me:
Combat start: Listen up pal / sunshine, this place is under MY watch!
During the mission Defeat Ajax:
First Psionic Projector Destroyed: Agh...hah...is that it, Character?! It'll take more than that to put me down!
Second Projector Destroyed: You're...nothing...I didn't survive the Rikti War...to be beaten by YOU!
Fourth Projector Destroyed: Maybe you're the one...huh? Who's gonna kill me? You think you're the ONE?! PROVE IT!
"Ajax has become vulnerable!": COME ON! HIT ME WITH EVERYTHING YOU'VE GOT!
At 75% Life: I haven't felt pain in a while, Character. I'll give you some credit for that.
At 50% Life: But you can't put me down, this is all just temporary. I'm immortal, unkillable!
At 25% Life: Even if I fall here...I'll still return...that's my fate...!
Defeated: What...where am I...going...?!
Upon the opening of the Omega Team's capsule, and the revelation of Ajax's true identity, a warrant was put out for Valetti's arrest. He fled to the Rogue Isles, where he started taking down as many super-powered criminals he could find. After being defeated during Dean MacArthur's arc, he is recruited by the writer of the Ouroboros Letters to defend against the Menders and the Coming Storm. What happened to his helmet is unknown.