* AccidentalInnuendo: The show has Kevin uttering the line "I don't know if I can pound your Grandma!" He means he's unsure he can fight her ...but ''still''.
* AlternateCharacterInterpretation:
** Gwen's and Kevin's crushes on each other are just their way of repressing that they're both attracted to Ben. Both attractions are at least partially taboo -- Gwen's because [[KissingCousins Ben's her cousin]], Kevin's because [[HoYay Ben's a guy]] -- so the only solution is to try to force themselves to fall (however [[StrangledBytheRedString improperly]]) for each other. Because they're both lying to themselves and each other, they're both getting their [[MasterOfTheMixedMessage signals returned]], which is encouraging the charade. This explains why Gwen tells Kevin to ask her out without wanting him to, why Kevin tries to make himself appear attracted to Gwen without making a move, and why they both show Ben so much more subtle and genuine affection.
* AngstWhatAngst: Despite Grandpa Max apparently dying in Season 1, Ben and Gwen's fathers don't seem to be in particular mourning over him. To be fair, they're only seen in one episode apiece, but one such episode ("What Are Little Girls Made Of") does reference what happened to Max quite a bit.
** Also, right after he seemed to die, Ben and Gwen ''immediately'' composed themselves. No tears, no anguish, no nothing.
* BadassDecay: Kevin and Vilgax suffer a lot of this. The general consensus is that Kevin got better in Season 3 (something that is even lampshaded in "Time Heals"), but Vilgax (ironically only featuring in that very season) never recaptured his former glory.
* BrokenBase: The series as a whole. While a lot of fans despised the show (see ContestedSequel above), some of them actually loved the DarkerAndEdgier take and found it an improvement..
* CharacterRerailment: Vilgax's characterization and voice (though the voice was done by JohnDimaggio rather than by Creator/SteveBlum) were a bit closer to how he was originally portrayed in [[WesternAnimation/{{Ben10}} the first series]] in the video game ''Vilgax Attacks!''.
* CopyCatSue: Albedo is a possible [[ParodiedTrope parody]]. He got a second Omnitrix, helped create the original, comes back with even more powerful version of it and he got an [[PaletteSwap incredibly simple design]].
* ContestedSequel: Quite a few people treat ''Alien Force'' as this and thus FanonDiscontinuity, mostly because of stuff like [[TheyChangedItNowItSucks making Gwen's magic powers into alien energy manipulation]] and [[RetCon that a lot of things in]] ''[[RetCon Alien Force]]'' [[RetCon don't match up and even ignores stuff established in]] [[WesternAnimation/{{Ben 10}} the original series]]. Still, some fans ''did'' appreciate this sequel, as noted in BrokenBase above.
* CrazyAwesome: Rath practically ''runs'' on this trope.
* CreepyAwesome: Darkstar was complete NightmareFuel in his first episodes, and it definitely played in his favor to make him popular.
** To a lesser extent, Big Chill.
* CrowningMomentOfAwesome: Rath [[spoiler:diving into the giant [[WesternAnimation/TeenTitans Trigonesque]] alien to rescue the Tiffin and escaping by punching the guys teeth out from the inside and threatening to "knit [his] organs into a sweater" if he tries to retaliate.]]
* DamselScrappy: Julie is perceived like this by some fans, but it's mostly an undeserved reputation caused by WhatMeasureIsANonBadass; she actually got kidnapped only thrice over the course of ''five'' season, which is fairly low as far as Super-Heroes' {{Love Interest}}s go, and, by the time she got Ship, she was perfectly capable of defending herself of her own.
* DracoInLeatherPants: Albedo, though easily explanable due to his IneffectualSympatheticVillain status.
** Darkstar is an even bigger case, and unlike Albedo, he doesn't have ''any'' sort of redeeming features.
* [[GermansLoveDavidHasselhoff English Love Alien Force]]: While the show is seen as a ContestedSequel in USA, it generally was a much bigger hit than its predecessor in the United Kingdom.
* EnsembleDarkhorse: '''You like Rath, dontcha?''' '''[+Everyone likes Rath!+]''' '''[++[[BoldInflation You know what happens to people who don't like Rath]]? [[CatchPhrase LET ME TELL YOU SOMETHING]], GUYS WHO DON'T LIKE RATH!!!++]'''
** [[CreepyGood Big Chill]] also is fairly popular amongst fans for his cool design, similarities to Ghostfreak and good voice;
** Albedo, who rarely appears, is surpisingly popular among the fans too, as mentioned previously. In fact, he was so popular, ''WesternAnimation/Ben10Omniverse'' raised him to BigBad rank for an entire arc.
** And let's not forget time-travelling [[Series/DoctorWho the Doctor]] {{Expy}} Paradox, whose even most of the Alien Force haters actually ''love''.
** Fangirls and the furry fandom consider Argit as this.
** Reinrassic III; granted, he is an important character, but he only had three appearances in the whole show. Yet you would be surprised to see how many fanart there are of him.
* EvilIsCool: Not as many cases as the Original Series, but the show still gave some fairly memorable villains. The Highbreed and Darkstar come in mind.
* EvilIsSexy: Still Charmcaster. Ben and Kevin even lampshade it in the episode she appears in.
-->'''Ben''': Was she cute?
-->'''Kevin''': More than cute; hot!
** Michael Mourningstar too, when he doesn't have his zombified face.
* FanPreferredCouple: If you haven't already noticed that there's a large fanbase who hates Kevin/Gwen and wants Ben/Gwen, this is probably the first time you've ever visited Tv Tropes (though oddly, Ben/Julie isn't quite as reviled after Julie got RescuedFromTheScrappyHeap.)
** There are quite a few who want [[HoYay Kevin/Ben]] as well.
* FoeYay: Gwen with both Darkstar and Charmcaster. Ben and Kevin qualify as "Former Foe Yay".
* FridgeHorror: Imagine being Alien X. You're [[PhysicalGod all-powerful]], [[RealityWarper capable of bending time and space]]... and unless [[LawfulStupid the voices in your head agree to do anything]], you're [[TakenForGranite stuck in place]], [[AndIMustScream forced to stand by]] while [[ApocalypseHow horrible things happen]].
* GeniusBonus: The Tiffin. If you know what the term means then it's no surprise that [[spoiler: he's going to be eaten.]]
* GrowingTheBeard: Season 1 didn't really have a clear story arc and included many fillers. Season 2 improved things a bit, continuing previous episodes, giving a slightly clearer progression, rescuing Julie from the Scrappy Heap and actually concluding to a real finale. Sadly, [[SeasonalRot season 3 didn't work that well]].
* LikeYouWouldReallyDoIt: Nearly averted with [[spoiler: Max]], whom they ''were'' planning on killing off, but decided not to.
* LoveItOrHateIt: The show is either loved for bringing a new more mature approach to the series and making Ben [[TookALevelInBadass significantly more badass than in the Original Series]], or hated for its difference with the Original Series and the poorly-written romance. Everybody, though, seems to agree about hating [[SeasonalRot Season 3]].
* {{Misblamed}}: When many of fans of the original Ben 10 complained about the questionable changes, they often blamed [[ManOfActionStudios Man Of Action]] for it. Despite the fact Man of Action has little to nothing to do with this show or any other beside the original except serving as executive producers.
* MemeticLoser: As noted in NeverLiveItDown, [[ArchEnemy Vilgax]] is constantly seen as a poor villain and a joke in this series due to the VillainDecay he suffered. While said decay is real, it's nowhere near the level fans tend to attribute him.
* MemeticMolester: Darkstar could almost rival [[WesternAnimation/TeenTitans Slade]] in this department.
* MemeticMutation: "BRING ME CHILLI FRIIIIIIIIES!"
** Also, Rath's "Lemme tell yah something" catchphrase have become quite popular.
* {{Narm}}: Vilgax's so-called ultimate form? [[spoiler:A giant green octopus.]] Sad because it could have been a great scene if not for limited efforts on the design and a fight that is not even seen onscreen.
** Ragnarok pretty much loses all credibility when itís revealed the key he was looking for [[spoiler:goes in his ''forehead''.]]
* NeverLiveItDown: While Vilgax ''did'' suffer DiminishingVillainThreat in Alien Force, he still had his share of BadAss moments, including having a CurbStompBattle with all the Plumbers Helpers ''and Max'', defeating several of Ben's most powerful alien forms (Jetray, Big Chill, Humongousaur and Chromastone) one after the others, destroying a whole ship of his own to free Ghostfreak, having a decent fight with Ghostfreak (which [[spoiler:he won]]) and [[spoiler:actually getting the Omnitrix in the finale, which led to the show's DarkestHour]] . However, the only things most fans retain about his Alien Force incarnation are that he was following a Galactic Code (even through both the series and WordOfGod shew he did it only out of PragmaticVillainy) [[spoiler:and that he got defeated by Diamondhead, who couldn't even scratch him before]].
** While Julie did got RescuedFromTheScrappyHeap, a lot of Alien Force haters just aren't willing to accept her and still consider her a SatelliteLoveInterest.
* PanderingToTheBase: Season 3 is this to fans of the original series who didn't care for the more mature direction that ''Alien Force'' went with in the first two seasons. This... [[SeasonalRot didn't work out quite well]].
* ParanoiaFuel: The [=DNA=]liens can use ID masks to disguise themselves as whoever they want in order to infiltrate and invade the humans right under their noses. They can literally be anyone, and ''Max Out'' reveals [[spoiler:they can turn humans into more of them]]. They can basically be anyone and anywhere.
* PortmanteauCoupleName: Gwevin (Kevin and Gwen), Benlie (Ben and Julie), Bevin (Ben and Kevin), Bwen (Ben and Gwen).
* RelationshipWritingFumble: The KissingCousins "relationship" of Gwen and Ben is not only back, but it becomes a "love triangle" by adding HoYay between Ben and Kevin.
* RescuedFromTheScrappyHeap: General opinion is that this happened to Julie midway through season two.
* RomanticPlotTumor: Gwen and Kevin, quite often.
* TheScrappy: Julie was this for a while, but got RescuedFromTheScrappyHeap midway through the second season.
** There are many who don't like the Anodite species as a whole, due to what is felt to be a pointless, as well as sometimes incredibly confusing Retcon, with the representatives of the species not being very well-regarded either.
* SeasonalRot: The third and final season seems to be the least popular overall, mainly due to Vilgax's DiminishingVillainThreat; even after it (mostly) came back in the GrandFinale, the [[spoiler: actual fight between him and Ben was seriously disappointing, despite the rest of the finale being awesome]]. Not that it's ''entirely'' hated though, as it ''did'' introduce us to [[EnsembleDarkhorse RATH!!!]]
* StrangledByTheRedString: Gwen and Kevin -- The ship is dropped on the viewer with absolutely no set-up, no basis, no rationality ''in the very first episode''. Kevin almost wrecking his precious car to tell Ben not to be rude to Gwen could be attributed to his BadassDecay, but "I'll follow you anywhere"? Were the writers afraid that if they took the time for some actual development, the show might be canceled before their new favorite couple actually got together?
* TearJerker: [[spoiler:Magister Labrid's death]] in the pilot.
** At the end of ''Alone Together'', Reinrassic III chosing to stay on the planet rather than just come back home with Ben. [[spoiler:He gets better fortunately]].
** [[spoiler:Ben's HeroicSacrifice in ''Time Heals''.]]
* TheyWastedAPerfectlyGoodPlot: The whole "Form A Team Of Plumber Kids".
** And even what they did of this plot didn't amount to much. For a series called ''Alien Force'', the only major things thing they did was fight the Highbreed at the end of season 2, get their asses handed to them by Vilgax at the beginning of season 3 and then got [[PutOnTheBus sent off to the Plumber Academy]] after "Above and Beyond". One must wonder what the point to this plot was when pretty much everything important amounted to Ben, Gwen and Kevin (and Max after season 2) doing all the work.
** Some people complained about things that are established, but are just dropped, or otherwise not elaborated upon (Why Ben decided to remove the Omnitrix, which could have tied into him wondering if his job as a hero is worth it, Kevin being EasilyForgiven and almost entirely trusted, among a few other things.).
* TheyChangedItNowItSucks: ''Everything'' has been blamed to be this at least once, from Gwen's alien origins to the Omnitrix's new shape, without forgetting Vilgax's new design, the characters' change of personnality (especially Kevin), and the list goes one.
* UglyCute: Argit. There are some people out there (mostly fangirls and furries) who adore him.
* UnpopularPopularCharacter: Argit again. In-universe, he is despised by almost everyone, and seems to have people who want him dead in every part of the galaxy. On the fandom side, on the other hand, you would be surprised to see how many fans love him. Even Derrick J. Wyatt, the one in charge of Ben10Omniverse, admitted he thought Argit was the best thing that came out of the Alien Force/Ultimate Alien era.