Spider-Man/X-Men: Time's Arrow (Book 3) (2001)

Story: Tom DeFalco & Eluki Bes Shahar

Spider-Man teams up with the X-Men to stop Kang from becoming the ultimate ruler of time! Our heroes jump from timeline to timeline, fighting off Kang's forces, and a few unexpected guests along the way. (Note: This is a novel, not a comic book. I haven't actually read it yet...but I've been told that the Iron Man of 2020 appears here, and has a rematch with Spider-Man!)

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Avengers Forever #11 (2001)

Pencils: Carlos Pacheco
Inks: Jesus Merino
Story: Kurt Busiek

Kang and the Avengers continue their battle against the Time-Keepers, who summon "evil" Avengers from multiple alternate timelines. The Iron Man of 2020 is among one of these characters brought in to do battle against the Avengers.

Universe X #X (2001)

Pencils: Dougie Braithwaite
Inks: Bill Reinhold
Story: Jim Krueger

The final battle looms, but the Absorbing Man takes the noble path instead, sacrificing himself to save the planet. Death is destroyed, and the construction of Paradise begins. The Iron Man of 2020 appears towards the end of the book, in a vision of things to come.

Paradise X Special Edition (2001)

Art & Story Concepts: Alex Ross

The Iron Man of 2020 is one of X-51's Heralds. These are beings charged with warning as many alternate Earths' Reed Richards as possible about the Celestial embryo growing within the planet. The team also includes Hyperion (from Squadron Supreme), Killraven, Bloodstorm (from Mutant X), Deathlok, Spider-Girl (from MC2), and Wolverine (from Days of Future Past).

Paradise X: Heralds #1 (of 3) (2001)

Story: Jim Krueger
Art: Steve Pugh

Machine Man pulls his Heralds from various timelines...one of whom is the future Iron Man. Pairing off his team, Machine Man sends them each into an alternate reality to warn the Reed Richards there of the growing Celestial embryo within their world. Iron Man is teamed up with Bloodstorm (from the Mutant X universe), and they get sent to a strange world where everyone—including Reed Richards himself—is a vampire!

Paradise X: Heralds #2 (of 3) (2001)

Story: Jim Krueger
Art: Steve Pugh

The teams sent to multiple realities aren't doing so well. Hyperion kills all who oppose him on his mission; Killraven gets seduced by Satyrnine; and Iron Man kills the vampire Tony Stark! All the worlds they visit are already doomed, so the teams return back to X-51's moonbase, and discover that the Watchers have come to deal with Uatu.

Paradise X: Heralds #3 (of 3) (2001)

Story: Jim Krueger
Art: Steve Pugh

X-51 discovers that Reed Richards is not the key in warning the various parallel worlds about the Celestials...the Watchers are. When a world discovers that it is being Watched, then the occupants there subconsciously plan to save their world. X-51 uses his powers to transport the Watchers that were after Uatu to different worlds, thereby making them guilty of the same crime, and saving the respective worlds. X-51's Heralds can finally find what they're looking for...except for Hyperion. He still wants to die!