Ben Tennyson's Universe is an alternate parallel universe where the series Ben 10: Ultimate Alien takes place. It is only seen and mentioned only in flashbacks. It is later seen in the comic Hero Times Two.
In Ben's world, no one from Rex's world exists. There was also no Nanite Event; thus, EVOs never were created and alien contact was established. In this world Providence doesn't exist but the Plumbers do, which seem to replace Providence in this world (but the Plumbers are human, aliens and human/alien hybrids and functioned in all parts of the universe); however, they are secretive to the general public on Earth.
In this universe Ben is known as "Ben 10, the biggest hero of the world", and his Ultimatrix is considered one of the most powerful alien devices in the universe.
It is revealed that Caesar banished Alpha to what he thought to be empty space since he attempted to possess living things. This space turned out to be the Null Void. Alpha found a host (Ben described it as a mecha-monster) and escaped this prison to Bellwood. According to Ben, he was at a celebrity gig when a portal in the sky opened up releasing Alpha. Ben turned into Humungousaur to battle it and some time in the battle they were transported to Rex's dimension.
After Alpha was defeated, Ben dropped off Alpha at the Null Void before heading back home.
- Ben Tennyson
- Gwen Tennyson
- Kevin Levin
- Max Tennyson
- The Plumbers
- Various alien species in the Ultimatrix
- Various types of Mutants
Technology and science
- Null Void Projector