- Confirmed in "Exclamation Strikes Back", although no reasoning has been given thus far.
- Most likely Jossed, since Hiromi happily accepted Kevin's offer to go out on a date in "Game Changer", and while Hiromi called things off when Kevin failed to show up at the date in "Exclamation Strikes Back", she did reveal that she did like like him.
- Confirmed: Ever since "The Bitter Sitter", some episodes have Bailey not only be more involved with Gretel's superhero missions, but also actively aiding Gretel and the rest, whether directly or not.
- La Cebolla: She's the only other human to be given powers by the aliens besides the hero and villain duos so she could return as another arch enemy and be connected to the lore regarding the UFOs.
- Confirmed
- The Neighslayer: He never went to jail or was desecrated, he simply got punched in the face, so the show will probably keep him around as a nuisance.
- Earworm: The show will definitely have plotlines involving him hypnotizing and mind controlling people, not necessarily just Hamster & Gretel. There's possibly a plot where he'll be hypnotizing the entire town to take over and defeat Hamster & Gretel.
- Confirmed
- Haggerty: Similar to Macarthur, every plotline has Haggerty working at a different job and scheming a grand crime plan.
- Dr. Eelgood: Plotlines involve him using a different evil eels.
- X-Terminator: He never went to jail and was simply crushed by the giant hamster ball. Likely he'll be in episodes related to different ways to wipe out all rodents.
- Copycat: He'll return, this time with a waterproof catsuit.
- The Imposter: Every episode he's in has him in disguise as someone else to get into Hamster & Gretel's secrets. There may even be an episode where he disguises as the heroes in order to frame them.
- Confirmed.
- Record Scratch: She will be revealed to be a real person, and have a proper appearance as a villain against Hamster and Gretel. Additionally, she may be extremely pissed at The Imposter for stealing her grand entrance in the villain world by pretending to be her just as part of an overly elaborate scheme for a prototype tank (although this may have little to do with her own evildoing).
- Crimson Haste: Could also be involved with that running villainess from the beginning of "Superhero Sibling Rivalry" due to both of them having Super-Speed and being clad in a reddish color.
- Tchotchke Jones: One of the leaked (preliminary) Season 2 episode titles is "Silence of the Tchotchkes", possibly hinting at the return of Tchotchke Jones.
- Inga The Ice Queen:' Plotlines will involve her freezing people and turning them to ice similar to Mr. Freeze.
- Mary Mitosis: Everytime she appears it involves her duplicating herself to commit crimes and she learns from her previous encounter by having her copies not deal with the cold and possibly similar to Lady Reduntant Woman she also is able to duplicate other people.
- La Somberona: Every plot line involves her trying to making every sad and miserable and there may be an episode where Hamster and Gretel have to deal with La Sombrerona and The Nightmarionette who are working together to bring people's most tragic fears to life. There may also be The Reveal that her five husband being killed by the tigers was a lie and she actually killed them.
- Rat Burglar: Wants revenge on Hamster & Gretel for ruining her son's spelling bee.
- Itsy Bitsy: Similar to La Cebolla, she was given powers by the aliens so she could return as another arch enemy and be connected to the lore regarding the UFOs. There could also be plenty of Spiderman references involving her such as the police chief congratulating Hamster & Gretel resembling J Jonah Jameson or her using venom as a weapon.
- Modros The Annilhator: A (possibly) tentative title for the Season 2 finale has been leaked to be "Who's Afraid of Mordros the Annihilator?" It's possible that "Mordros the Annihilator" will be a recurring character in Season 2 and might be this greater evil's name.
- Villains and antagonists that have been Confirmed to have returned since, but not specifically guessed before are Van Dyke (who still wished to take over the world, but specifically targeting Mayor Meyer instead of Gretel by possessing an underwear model and stealing away Veronica Hill's potential spot as lead correspondent with his host's good looks and his own wits), as well as Tina (who teams up with Grobla and Gerbil to kidnap teenage video game playtesters (Kevin, Hiromi, Fred, Anthony) for a new mission, to restore her honor since she failed her previous mission). A cake topper of Big Baby had also cameo'd but hasn't really made a physical appearance yet.
- Gretel and/or Hamster face off against either a Modified Clone, a mechnical double (created by some other villain) or a straight up Evil Doppelgänger from a Mirror Universe.
- Possibly any of Gretel's friends or family might have a Face–Heel Turn and become evil villains.
- The Power granting Aliens look like they might be a huge antagonist and possibly the Final Boss in the show
- An Incredible Hulk Expy who changes into a monster whenever they are emotional
- A Monster Clown Villain
- A Villain from another world that traveled to Gretel's
- A villain from the past that ended up in the present day through either time travel or being thawed out.
- It may very well be the power-granting aliens, since they're seen at the end of the first episode giving powers to another duo, and explicitly telling them to use their powers for evil! It's possible there's some kind of large-scale experiment going on...
- "Exclamation Strikes Back" reveals the reason for the aliens giving powers to other villains being that they're meant to train Hamster and Gretel in order to fight against an even greater evil in "the next season", so this might be the series-wide Big Bad. A (possibly) tentative title for the Season 2 finale has been leaked to be "Who's Afraid of Mordros the Annihilator?" It's possible that "Mordros the Annihilator" might be this greater evil's name.
- Kevin: The same enemies as Hamster & Gretel
- Gretel: Another little girl with a pet, who the aliens with grant them powers, but for evil instead of good.
- Gretel gets something like that in Tina from "Sleepover with the Enemy", a Bolgylvanian spy (who has a cyborg gerbil for a pet) who was tasked to kidnap Bailey's dad to produce a good video game for the nation, and who herself wants to make Bailey her best friend after her own best friend Grobla was sent to space. She matches Gretel in power not with alien superpowers, but with high-tech Bolgylvanian weaponry. After Gretel brings Grobla back, however, Tina decides to abort the mission and go back to Bolgylvania, so it's unlikely she's supposed to be Gretel's true arch-enemy.
- Hamster: The pet of this evil little girl, who instead of being cute like Hamster, is a monstrosity.
- Hamster gets something like that in Gerbil from "Sleepover with the Enemy", who Tina's pet gerbil-turned-cyborg. He matches Hamster in power not with alien superpowers, but with high-tech Bolgylvanian weaponry. Like how Tina did a Heel–Face Turn after reuniting with Grobla, Gerbil has seemingly patched up with Hamster, so it's unlikely he's supposed to be Hamster's true arch-enemy.
- Given their supervillain origins are remarkably similar to those of Hamster, Gretel and Kevin, perhaps the Destructress and FistPuncher were meant to be their shared Evil Counterparts, possibly their main rivals or archenemies too. They are at the very least their Foil. Their powers are very similar to those of Hamster and Gretel, and since they are capable of bestowing people with different superpowers (e.g. they gave La Cebolla the ability to "talk to onions"), this might as well be deliberate.
- Kevin: Will likely be a teenage boy with superpowers who unlike Kevin is a jerk to his siblings and treats them like trash. He's essentially a more successful Kevin. Both are ambitious, took their families for granted, and developed animosity towards their siblings. However this person lacks any of Kevin's redeeming qualities, such as being willing to recognize and work with Hamster and Gretel.
- Gretel: Another little girl with a pet, who the aliens with grant them powers, but for evil instead of good.
- Gretel gets an Evil Counterpart in Tina from "Sleepover with the Enemy", a Bolgylvanian spy (who has a cyborg gerbil for a pet) who was tasked to kidnap Bailey's dad to produce a good video game for the nation, and who herself wants to make Bailey her best friend after her own best friend Grobla was sent to space. She matches Gretel in power not with alien superpowers, but with high-tech Bolgylvanian weaponry. After Gretel brings Grobla back, however, Tina decides to abort the mission and go back to Bolgylvania, so it's debatable whether or not she's still an Evil Counterpart.
- Hamster: The pet of this evil little girl, who instead of being cute like Hamster, is a monstrosity.
- Hamster gets an Evil Counterpart in Gerbil from "Sleepover with the Enemy", who Tina's pet gerbil-turned-cyborg. He matches Hamster in power not with alien superpowers, but with high-tech Bolgylvanian weaponry. Like how Tina did a Heel–Face Turn after reuniting with Grobla, Gerbil has seemingly patched up with Hamster, so it's debatable whether or not he's still an Evil Counterpart.
- Given their supervillain origins are remarkably similar to those of Hamster, Gretel and Kevin, perhaps the Destructress and FistPuncher were meant to be their shared Evil Counterparts, possibly their main rivals or archenemies too. They are at the very least their Foil. Their powers are very similar to those of Hamster and Gretel, and since they are capable of bestowing people with different superpowers (e.g. they gave La Cebolla the ability to "talk to onions"), this might as well be deliberate.
There could be at least two ways it could happen:
- The aliens just bestow a random person with superpowers, and the person refuses to do evil. Either the aliens will immediately write off the experiment as a failure, or they'll force the person to do evil anyway, perhaps with Mind Control.
- If the aliens always do a background check first before bestowing someone with superpowers, then it's possible they will bestow a good-doing civilian by mistake, and will desperately attempt to depower them, since this wasn't the plan.
- Jossed as the villain's backstories have nothing to do with Hamster & Gretel.
- If they defect from evil, there's also a chance that Lauren and Lyle will disown their supervillain names and costumes.
- Between the fact that the beam of light landed on Kevin and Gretel, and they didn't give any indication that they were planning to skip over Kevin and give Hamster the powers instead, it seems more like Hamster got powers via a freak accident than a legitimate gift from extraterrestrials.
- Jossed, if Kevin's Theme Song Takeover indicates anything. The aliens come back to Kevin, just to announce he's been chosen to take over the theme song. When Kevin complains about being skipped over and begging the aliens to give him superpowers as well, the aliens outright refuse him, stating that they're not bestowing their superpowers to anyone willy-nilly... even when they're exactly doing that with a fire hydrant in that very moment.
- Officially Jossed at the end of "Exclamation Strikes Back". The aliens outright tell Kevin that they never intended to give him powers.
- In the ending of "Exclamation Strikes Back", the aliens state that Hamster and Gretel have to defeat an even greater evil in the next season, than the villains they already faced throughout the past season, so it's at the very least tied to a Story Arc spanning over at least two seasons.
- Not that likely, because two distinct voices come from one saucer at the end of "La Ballad of La Cebolla" (one voiced by Dan Povenmire, the other by Joanna Hausmann. This means that either, each UFO has at least two different personalities (each with a distinct voice) programmed inside of it, or, more logically, there's just at least two beings inside the UFO.
- Carolina being one of the aliens makes it harder to explain away relatives on her side of the family like her mother and sister. Same with Dave and his side of the family, such as his great-grandfather, his sister Stacy and niece Fred.
- This WMG doesn't make any sense anyway when you realize the following:
- The characters in question have completely different voice actors (Dave and Carolina are voiced by Matt Jones and Carolina Ravassa, while the aliens are voiced by Dan Povenmire and Joanna Hausmann).
- There have been instance where the aliens are present in their UFO while we know about Dave and Carolina's presence elsewhere (i.e. they have an alibi); such as in "The Unnatural History of Dr. MedusaSaurus Ph.D", in which the aliens shoot a superpower beam over a tar pit on top of the museum while Carolina was with Michelle (Bailey's mom) in the museum cafeteria the whole time.
- The reason why the aliens are "mysteriously absent" from their UFO for most of the episode until the very end is because the UFO for most of the episode is actually NOT their actual UFO, but a decoy they planted in Area 51 for FistPuncher and The Destructress to hijack; this is evidenced when we see the aliens' UFO's dashboard at the end of the episode, which features a completely different set of controls (with lots of sticks and buttons akin to a plane cockpit) than the other UFO for most of the episode (with features a steering wheel much like a car, so Kevin can take control of the UFO with ease). It can be assumed that the aliens never left their own UFO in the first place.
- Just like the male and female aliens, respectively, Dave is a bit off his rocker while Stacy is the more sensible one.
- If they are the aliens granting powers that would make their last name, Grant, a Meaningful Name.
- Seems unlikely. Stacy and the female alien may share a voice actress, but Dave and the male alien don't. The male alien is voiced by Dan Povenmire, but Dave only LOOKS like Dan Povenmire: he's actually voiced by Matt Jones.
- If Aunt Stacy is the Alien Commander, or a relative of hers, then when she told Fred that positiveness runs through her veins she could have been speaking literally about the positive probability ions Octalians have.
- Unlikely, the Octalians have a completely different design for their spaceships: they're oblong and feature tentacles, whilst the recurring UFO resembles the more typical flying saucer.
- Bonus points if the aliens not only resemble the two, but are also even named after them: something like Nad and Annaoj or something.
- If the show is successful, it is likely.
- You can actually spot Melissa's Dad, Richard in the second episode, though he has a slight redesign and he's voiced by Povenmire instead of Adrian Pasdar. Seems like the callbacks are already starting.
- Confirmed, mostly on the Phineas and Ferb side. Characters like the farmer and his wife, Love Händel, and even Doofenshmirtz make voiced cameos, most related to their roles in Phineas and Ferb. Aglets were also mentioned once. Less so with Milo Murphy's Law, however: there's a Dr. Zone movie poster, but no actual character cameos beyond a recolor of Brigette Murphy serving as a background character, not unlike the fireman chief resembling Mr Chase.
- Alternatively, the talking zebra will appear and call Kevin "Candace".
The second season could give out some possibility adventures on what could happen during next upcoming season.
- Kevin explaining to Hiromi about Gretel and Hamster being superheroes.
- The identification on who the greater threat could be that Hamster and Gretel will encounter.
- The other villains who appeared only once from the first season returning to get revenge of the duo or maybe becoming good.
- The relationship between Fred and Naya.
However he ended up not being able to have superpowers, doesn’t get any respect, and even gets dumped by his own crush despite having just asked her out with The Aliens even revealing that he never was supposed to have powers.
Because of all that happened to him, this can make very sense for that Greater Threat to convince him on joining them so that he won’t have to be disrespected or be abused and that they will give him superpowers.
- Or alternatively, Kevin is the greater threat, finally having enough of being pushed around by literally everyone for no reason and deciding to take revenge.
- Another alien species that are a great rival to the aliens we see - It's likely Gretel gave superpowers as well as the other villains to prepare her for an another alien species that are a threat to both the power granting aliens and Earth.
- Another person granted powers: The Aliens are experimenting to see if they can make people as evil and wicked as possible with Fist Puncher & The Destructress, La Cebolla, and Itsby Bitsy as early tests. After seeing all of those fail, the aliens want to go full turbo on powers and grant someone with the most horrid and cruelest powers who can serve as the greatest threat to Hamster & Gretel.
Either way, the greater threat proves to be too much for Hamster and Gretel alone to handle, so the aliens make the difficult decision also grant superpowers to the friends that helped Hamster and Gretel fight the previous villains, in order to ensure the villain's defeat; this will most likely happen in the finale for Season 2. Kevin was already promised to get superpowers at some point in the future, and depending if it's temporary or not, Kevin will regain those superpowers or may still have kept them. This decision furthermore results in Fred and Bailey also getting superpowers, and, depending on if they're let in on Hamster and Gretel's identities, perhaps Hiromi and Anthony as well, and maybe even Nordle.