Enter Rex Salazar. Rex patrols the ruins, using his "Builds" (massive machines sprouting from his body) to contain EVOs. He spots Ben (as Humungousaur) and mistakes him for a massive, rampaging EVO. The two titans clash in a spectacular, debris-filled brawl that defines the first act.
The between the 2011 crossover and the 2021 reboot version
Ben 10/Generator Rex: Heroes United is widely regarded as one of the best crossover events in Cartoon Network history. Released in 2011, this one-hour special successfully blends the high-stakes sci-fi of Generator Rex with the alien-shifting action of Ben 10: Ultimate Alien Critical & Fan Reception Visual Excellence: Fans praise the decision to use the Generator Rex
But this wasn’t just a cash-grab. It was a love letter to both fanbases that remains one of the most ambitious animated crossovers ever made. Here is everything you need to know about this hidden gem.
Here's a brief summary:
They discover that the rift also brought through a sentient, parasitic nanite named , created by Rex’s brother Caesar. Alpha seeks a permanent physical form and begins absorbing machines and nanites, eventually reaching the Bug Jar to consume its entire population. To defeat this colossal threat, Ben and Rex must combine their unique abilities in a final, high-stakes battle. Key Characters
Heroes United wasn't just a marketing stunt; it was a love letter to the "Man of Action" era of animation. It proved that these two shows shared the same DNA (literally and figuratively) and left us all wishing for a full-blown sequel series.
(Ben vs. Rex or the final Alpha battle)