The Null Void is an alternate dimension created by the Galvan as a penal colony. It is filled with what look like never-ending floating rocks. Null Guardians are the guards of this prison dimension.
The Null Void is normally accessed by a Null Void Projector. Max is a known Null Void holder. He and his former partner, Phil, have owned one and trapped thousands of aliens in it while in their Plumber years. If a projector is broken and someone tries to use it, it self destructs immediately, similarity to a hand grenade, but with far greater force; Everything within a half mile radius, as referenced in Alien Force episode 6, Max Out. It is possible to release aliens within the realm.
Later in Alien Force, it is discovered that settlers live in the Null Void as well the descendants of criminals who made a living there for years.
In Alien Force, D'Void seized control over the Null Void and attempted to break through into the main dimension by means of a kormite powered-drill, but was defeated by Ben, Max, Helen, Pierce, Manny and some other aliens.
In the Game, players begin at the Null Void for Basic Training. There is a plumber training camp there along with Ben and the Rust Bucket III.
The Null Void background in the character selecter is a glitch for when a player moves up a level to the Zoo or Mt. Neverest it would stay like that until the players move to Sector V, after training.
- Ben Tennyson-Imprisoned in episodes Back with a Vengengce, Voided, 'Single-Handed, ...Nor Iron Bars a Cage. (Been Freed and Escaped in each episode)
- Gwen Tennyson-Imprisoned in the episodes Back with a Vengence and...Nor Iron Bars a Cage
- Kevin Levin-Imprisoned when he was 11 in Back with a Vengence and again when he was Ultimate Kevin in ...Nor Iron Bars in a Cage (which he also escaped)
- Kevin 11,000-Imprisoned in the episode Ken 10.
- Vilgax-Imprisoned by Max in Back with a Vengence and Secret of the Omnitrix and imprisoned in Vilgax Attacks
- Psyphon-Imprisoned in Vilgax Attacks
- Phil-Imprisoned by Grey Matter in Truth but was freed after the original series
- DNA Aliens-Imprisoned in Plumber's Helpers and in Max Out
- Highbreed-Imprisoned in Max Out
- Max Tennyson-Imprisoned himself in Max Out and escaped in War of the Worlds
- Darkstar-Imprisoned in Darkstar Rising but was freed by Ben, Kevin and Gwen in War of the Worlds
- Dr. Animo-Imprisoned prior to Voided escaped in Escape From Agregor
- Albedo-Imprisoned in Good Copy, Bad Copy freed by Vilgax in The Final Batlte: Part 1
- Sunder-Imprisoned in Single-Handed but was freed by Azmuth in the Transmogrification of Eunice
- Helen Wheels-Imprisoned herself in Plumber's Helpers escaped in War of the Worlds
- Manny Armstrong-Imprisoned himself in Plumber's Helpers escaped in War of the Worlds.
- Ragnork-Imprisoned by Max prior to the original series escaped in Vendetta
- The Mummy-Imprisoned by Dr. Vicktor in Be Afraid of the Dark
- Dr. Vicktor-Imprisoned himself in Be Afraid of the Dark and then escaped in Absolute Power: Part 1. He was then imprisoned again by Ultimate Kevin in Absolute Power: Part 1. He later escaped in Viktor: The Spoils.
- Aggregor-Imprisoned offscreen at the end of Forge of Creation
- Alpha-Imprisoned by Ben after the events of Heroes United.
- Mutant To'kustars-Imprisoned by Blukic and Driba
- Tricia Romanov Tennyson-escaped too many times to count
- The Null Void seemed to be a horrifying/unpopular place, for example:
- Kevin was scared and horrified of going there.
- Ben claiming that being in the Null Void is much worse than being in prison.
- Argit hesitating to go there.
- Vilgax had an eye twitch by just mentioning it, calling it accursed.
- Tricia has stated she'd rather stay in the Romanov Thermos instead of the Null Void.
- It is confirmed by the authoress that both Tracy and Kenny have been in the Null Void with Tricia as kids due to a dare though ended up being grounded afterwards. Both Tracy and Kenny have mentioned it's worse than any other villain they faced with Kenny saying he'd rather be at Summer School and Tracy having to be stuck with any one of her rivals for a day including Tricia.
- The Null Void is similar to the Phantom Zone, an intergalactic prison in the Superman universe that keeps dangerous criminals, such as General Zod.
- For some reason, the Null Void is purple in the Original Series but red in Alien Force.
- In Omniverse, the Null Void's appearance is a mix of the Original Series and Alien Force.
- The Null Void is a setting in Ben 10: Galactic Racing.
- The Null Void's name is a play on the term null and void, which means "having no effect".
- It may be possible other villains the MCF girls faced have placed villains here. Though who they are is unknown.