|This article belongs to the Classic Continuity|
A retcon doesn't mean that a change is good or bad. A retcon is just new information that imposes a new interpretation of past events. Retcons aren't only limited to the changes that blatantly contradict on-screen information. Things can happen as the result of inconsistencies.
Ben 10: Alien Force
- The Plumbers are now an intergalactic police force, when it was established in the original series that they were a secret government organization comprised of humans only, several of which had a racist attitude towards aliens.
- The workings of Kevin's powers have been altered. Instead of the mutant ability to absorb, store, and redirect energy as well as DNA, Kevin reappears in Alien Force with the ability to absorb physical materials and form a shell of that around his body.
- Gwen is revealed to be part alien, which explains her proficiency in magic, beyond her spellbook.
- The Omnitrix's hourglass-like symbol was previously a hallmark of Azmuth and his inventions, seen in his clothing and suit. However, this was changed to represent all of Galvan.
- In relation to this, the Plumbers' badge is changed from being red to copies of the Omnitrix symbols.
- It was implied that Myaxx and Azmuth were one of very few involved in the creation of the Omnitrix. A far different picture is shown in Alien Force, where the Omnitrix's creation is portrayed as a funded publicly-known operation.
- Kevin cannot create a shell of material without a substantial amount to absorb, contradicting past events shown with him mass-producing Taydenite.
- Kevin's origins, compared to what was shown in the original series, have been altered for the series. He is now an alien hybrid, inheriting his powers from his father, Devin Levin, instead of getting them as a result of a mutation.
Crew Statements' Retcons
- The positioning of the Omnitrix/Ultimatrix symbols are the result of the devices working properly compared to the symbols' locations in the original series.[DM 2]
- Vilgax was originally stated to be 15 feet tall.[AC 1] However, Humungousaur at his base height of 12 feet is shown to be the same size as him.
- Gwen's mother's name is Natalie instead of Lily.[pop-up 1]
- In the original series, the Forever Knights were like "Anti-Plumbers", exploiting unusual threats instead of fighting them.[pop-up 2] In Alien Force, the Forever Knights are revealed to be highly xenophobic.
- Originally, Null Guardians were the only indigenous lifeforms in the Null Void.[pop-up 3] This is retconned with the introduction of the Null Void Settlers.
- Originally, the Omnitrix only held thousands of DNA samples.[pop-up 4] This was retconned two ways in Alien Force:
- The Chimera Sui Generi have been changed from what was established in the original series:
- All female Chimera Sui Generi had a dark "beauty mark" somewhere on their center face tentacle[pop-up 5], but none of the females seen in Alien Force have them.
- Most Chimera Sui Generi were trained from birth for combat[pop-up 6] and craved any chance for it[pop-up 7], but in this series, Vilgax states that most of them are innocent people.
Ben 10: Ultimate Alien
- Charmcaster's motivation is expanded upon, with her father seemingly driving her actions throughout the previous two series.
- Kevin's stepfather is actually a good person. Furthermore, Kevin was never kicked out of his house as a child, but went insane with power, destroyed the house, and ran away.
- Max describes himself getting recruited by an intergalactic form of the Plumbers, where it could have been assumed that the Plumbers originated from Earth and became intergalactic.
- The Nanochip queen featured in Ben 10: Alien Swarm is revealed to be a decoy created by the real queen to avert suspicion towards her. Elena's depiction is also heavily altered from what was shown in the film.
- Events of Ben 10: Race Against Time are retconned into an alternate timeline. As such, Eon's backstory has been changed (including his species). Furthermore, Chronians and the planet Chronia no longer exist in the Prime Timeline.
- While Azmuth's change in characterization in Alien Force compared to what was seen in the original series had not been explained prior, his entire demeanor is shown not to be the case of time's passage due to flashbacks.
- The Omnitrix featured in the original series and Alien Force is revealed to be a prototype; with Azmuth having been working on a new Omnitrix, which Ben gains at the end of Ultimate Alien.
Crew Statements' Retcons
- Originally, Alien X was not the most powerful being in the Omnitrix.[DM 3] This is retconned in Ultimate Alien, as absorbing the abilities of a Celestialsapien such as Alien X would grant Osmosians and other beings like Darkstar access to nigh-unlimited power.
Ben 10: Destroy All Aliens
- Although Gwen first performed a tracking spell when she was 15, it is actually shown that her first time performing such a spell was when she was 10.
Ben 10: Omniverse
- In Alien Force and Ultimate Alien, two out of Alien X's three personalities needed to agree in order to perform an action. In Omniverse, all three have to agree.
- Although it was established in Alien Force that Ben last saw Vilgax when he was 10, a flashback showed that he had an encounter with Vilgax was when he was 11.
- The Plumbers' Helpers now have different origins; they are shown to be humans whose appearances and DNA were altered when Kevin used his powers on them and their alien donors.
- According to Azmuth's Father, the pyramids were built by Tetramands. This was proven wrong in Omniverse, where an ancient stone tablet shows that the pyramids were in fact built by humans with the "help" of Blukic and Driba.
Retcons From Previous Series Explained
- The retcons made to the Omnitrix symbols in Alien Force are reversed. The limited positioning of the symbols were technical glitches in the original Omnitrix and Ultimatrix that caused the transformations to come out naked and cold. These glitches also granted them random abilities not native to the alien species. Fortunately, these errors were corrected in the current Omnitrix.[DJW 1] These powers glitches included:
- The retcons made to the Plumbers in Alien Force are explained and/or fixed. The original Earth Plumbers were a separate group until they joined the intergalactic Plumbers at some point between the events of the original series and Omniverse flashbacks.  While this helps with introducing alien Plumbers working at Earth bases, only the circumstances of Max joining the Plumbers remain unresolved.
- The Plumbers' badges' design have been reversed to look like their depiction in the original series.
- The retcons made to Kevin in Alien Force are reversed. While Kevin is still considered an Osmosian, the term actually refers to a subspecies of human with a unique genetic component that gives them powers rather than a different species. Also, neither Devin Levin, the planet Osmos V, nor the sun Osmos exist because they were all fake memories implanted by Servantis.
Crew Statements' Retcons
- Originally, Tetramands seemed fairly Bronze Age-y for their level of technology.[MW 2] This was retconned in Omniverse as Tetramands are shown to have a far more advanced civilization than humans.
- Originally, the citizens of Vilgaxia had their own opinions whether Vilgax is a hero or otherwise. However, nobody voiced their thoughts publicly for sure.[DM 2] This is slightly retconned when Milleous claims that capturing Vilgax would demoralize the people of Vilgaxia enough to make them surrender, and when the news is out that Vilgax succeeded in escaping, the Chimerans put up such a fight that the Incurseans are forced to retreat.
- Originally, Ultimate Echo Echo did not have the ability to duplicate himself.[DM 4] This is explained and/or fixed, as he can only duplicate himself using his sonic disks[DJW 3] and was unable to do so in Ultimate Alien due to a glitch with the Ultimatrix.[DJW 4]
- Originally, Vulkanus wore flesh-colored prosthesis in the original series.[DM 5] This was changed in Omniverse, as he was originally large and muscular like the rest of his kind, until his fight with Ben lead him to being caught in an Element X-induced explosion. Vulkanus survived, but his body was destroyed, leading him to be put into a regeneration suit until he finally grows to full size.
- Originally, XLR8 was the only Kineceleran on Earth because the slow rotation of Earth made other Kinecelerans sick after a few days.[pop-up 8] This is retconned, as several Kinecelerans reside in Undertown.
- Originally, the Anur System had an anti-matter sun.[pop-up 9] However, this is no longer true, considering the massive cobweb structures lining the system.
- In the original series, it was stated that all Loboan cubs had green eyes, whereas adults had red and pale orange eyes.[pop-up 10] This is retconned, as the Loboans seen on Anur Transyl have eyes of varying colors.
- Hex's skull facepaint was the same as that worn by the warriors of Bezel.[pop-up 11] This is retconned in two ways:
- The Charms of Bezel were not magic. Instead, they were advanced Bezelian technology that seemed magic to Earth.[pop-up 12] This is retconned, as Bezel is revealed to be a person.
Merchandise Information Retcons
- Rather than being brought to life by an environmental disaster[merchandise 1], the Galvanic Mechamorphs were brought to life after one of Azmuth's projects went awry. 
- Encephalonus IV was a gray, cloud-covered planet with lightning bolts constantly ripping through the sky in an unending electrical storm of spectacular cumulonimbus activity unrivaled by any in the universe.[merchandise 2][merchandise 3] [merchandise 4] This is retconned, as it is shown that the planet has relatively normal weather.
- The Necrofriggians used to be the only living beings on Kylmyys.[merchandise 2][merchandise 5] This is retconned with the introduction of the Psycholeopterrans.
- Originally, nothing actually lived on Anur Transyl.[merchandise 6] This is retconned, as Anur Transyl is shown to be inhabited by many species native to the Anur System.
- ↑ 1.0 1.1 Ben 10 Returns: Part 1
- ↑ Truth
- ↑ Big Fat Alien Wedding
- ↑ What Are Little Girls Made Of?
- ↑ 5.0 5.1 5.2 5.3 Ben 10: Secret of the Omnitrix
- ↑ 6.0 6.1 War of the Worlds: Part 1
- ↑ Darkstar Rising
- ↑ Kevin's Big Score
- ↑ Vendetta
- ↑ 10.0 10.1 Primus
- ↑ 11.0 11.1 11.2 Lucky Girl
- ↑ Ultimate Weapon
- ↑ Be-Knighted
- ↑ 14.0 14.1 Back with a Vengeance
- ↑ Voided
- ↑ And Then There Were 10
- ↑ 17.0 17.1 Ghost Town
- ↑ Where the Magic Happens
- ↑ Absolute Power: Part 2
- ↑ Moonstruck
- ↑ Revenge of the Swarm
- ↑ Ben 10,000 Returns
- ↑ Solitary Alignment
- ↑ The Ultimate Enemy: Part 2
- ↑ The Forge of Creation
- ↑ Ben 10 Returns: Part 2
- ↑ 27.0 27.1 Ben 10: Destroy All Aliens
- ↑ X = Ben + 2
- ↑ So Long, and Thanks for All the Smoothies
- ↑ Vengeance of Vilgax: Part 1
- ↑ Bengeance Is Mine
- ↑ Weapon XI: Part 1
- ↑ Fight at the Museum
- ↑ Greetings from Techadon
- ↑ Inspector 13
- ↑ The Widening Gyre
- ↑ 37.0 37.1 Malefactor
- ↑ The Rooters of All Evil
- ↑ Vilgax Must Croak
- ↑ The Ballad of Mr. Baumann
- ↑ Ben 10,000
- ↑ The More Things Change: Part 2
- ↑ Hunted
- ↑ 44.0 44.1 44.2 Rad Monster Party
- ↑ Benwolf
- ↑ Charm School
- ↑ 47.0 47.1 Third Time's a Charm
- ↑ Trouble Helix
- ↑ Of Predators and Prey: Part 1
- ↑ File:Lily Tennyson.png
- ↑ File:FK Exploit Unusual Threats.png
- ↑ File:Blind Null Guardians.png
- ↑ File:Omnitrix Merge DNA.png
- ↑ File:CSG Beauty Mark.PNG
- ↑ File:CSG Combat.png
- ↑ File:Myaxx Different.PNG
- ↑ File:Kineceleran Sick.png
- ↑ File:Anur Anti-Matter Sun.png
- ↑ File:Loboan Eye Color.png
- ↑ File:Hex Skull Facepaint.png
- ↑ File:Bezelian Technology.png