- Lola's alternative personality by 30%. On the outside, she seems like the stereotypical hammy princess-loving Girly Girl, but inside, she might've had a post-Split Personality-Creepy Childlike anger issue, or just an innocent kid with a slightly sensitive Split Personality that lashes out at others when thing don't go her way. Either that, or she's just Troubling Unchildlike Behavior INCARNATE. Or better still, both of the above. This, however, has been heavily toned down after the first season.
- Lola herself, upon some rare occasions, will make creepy and humorously mischievous Slasher Smiles. Although most of Lola's action are Played for Laughs, so it's not really too much of a creepy tactic. Also, keep in mind that Lola's voice actor is Grey DeLisle, the same person who voiced Vicky and Azula.
- Lisa as of season 2. While Lisa was always the one to conduct experiments, her actions became a lot more sinister in this season. This is the type of person who would willingly electrocute a baby, secretly experiment on her family members or harvest their organs without their consent all to sate her curiosity. That's not even getting into her weird fecal studies or how she has no qualms about experimenting on herself regardless if she dies or not. She actually has several physical handicapsnote as a result of her experiments. Keep in mind that Lisa is FOUR YEARS OLD. Also, she is quite sneaky and often lies about her human experimentations, such as changing the subject in regards to DNA samples or microchips. And lets not forget when she and Lincoln had GLOWING BRAINS.
- Luan during April Fool's Day. She becomes a prank-obsessed maniac, pulling pranks that can lead to very serious injury and the only one who finds it funny is herself. It's no wonder the Louds and Clyde are afraid of the holiday.
- In "Left in the Dark", when Lori points out that Lisa can't use her siblings as test subjects, Leni reminds her about an Noodle Incident in which this happened. For those too squeamish to click, essentially, Leni's face swelled up and broke out into zit-like pimples and pink boils, apparently due to one of Lisa's experiments. It's Played for Laughs, but still.
- In "A Tale of Two Tables", Lincoln's entire Nightmare Sequence about the grown-up table. The very worst parts are probably his parents' heads revealed to be roast turkeys, and the table chaining Lincoln up and dragging him down a dark purple vortex, the faces of his five older siblings surrounding him while chanting "ONE OF US...ONE OF US..." Fortunately, the episode ends completely differently.
- In "Changing the Baby", Lisa strapping Lily to a table to do who-knows-what to her simply because she was too young to resist!
- In "Hand-Me-Downer", Colonel Crackers, Luan's old dummy, with its unnerving face, who also may or may not be alive.Colonel Crackers (looking at the audience, with a threatening tone): "Listen to what he says, kids."
- "Along Came a Sister" has The Exterminator's Establishing Character Moment of gassing two innocent caterpillars for no reason.
- In "A Tattler's Tale", Lola's mannerisms are taken to a new extreme in this episode when she was blackmailing her other siblings into doing whatever she wanted. The worst has to be when she was forcing Lucy to drive her around in her car. When Lucy refuses, Lola slowly turns her head in an utterly chilling manner before informing her that she knew about her secret.
- In "One Flu Over the Loud House", some of the zombie-like imagery of the flu epidemic, including the infected girls' pale green skin and wonky yellow eyes. A special mention goes to Lynn Sr.; in order to keep the Running Gag of his full face never being shown, he's entirely in silhouette, except for his sickly yellow eyes.
- Then there's the rather realistic portrayal as to how fast a cold (or in this case, the flu) can spread. There's one particular scene where Lynn, having caught the flu from Lori, drinks some orange juice straight from the carton. Seconds later, Lana pours a glass of juice from the same carton Lynn just drank from, and as she tilts her glass, a close-up reveals germs in her drink, of which can be heard screaming as they slide down into Lana's throat.
- On the subject of diseases, there's a Licensed Game called "Germ Squirmish" which is about the Loud house being contaminated with germs that can be seen sprouting up out of nowhere. The music is very dramatic and if you lose, the Game Over screen shows Lincoln with the same flu symptoms as in "One Flu Over the Loud House" and a message about being sick. If you let too many germs fill a room, it gets too infected to enter and is cordoned off. One version involves seeing how long you can last in the basement and has even more dramatic music and Lisa nonchalantly says, "Let's see how long you can last."
- In "Snow Way Out", Flip was willing to let the kids, including a one-year-old child, freeze to death after Lana refused to give him her winning burger wrapper.
- "Sitting Bull": While on her first babysitting job, Lynn tells the kids she's watching a story about how she once fell twenty feet and broke her tibia, to the point where it could be seen sticking out of her skin; unsurprisingly, one of the kids pukes after she shares this.
- "Jeers for Fears": As a Halloween Episode, the episode is naturally full of scary stuff. Special mention goes to the Loud Sisters attempts to help Lincoln and Clyde toughen up for a haunted house they want to visit.
- "Middle Men" reveals that at least when Lynn was in sixth grade, the bullying situation was so bad that Lynn (and possibly others) had to warp their personalities to survive. This has permanently altered Lynn's psyche to the point that her sisters are scared of her because she can't turn off survival-at-school mode.
- "Friended! With the Casagrandes" has Ronnie Anne and her new friend Sid feeding pigeons in the park. One of the pigeons is shown missing a significant amount of feathers and a foot, which the pigeon coughs up.
Nightmare Fuel / The Loud House