Even though, as far as we know, babies are generally not considered as smart as children or adults, in fiction there is one thing that they can often infallibly sense: pure evil. If a baby is in the room when something bad happens, it will almost always start crying, even though there's no way it can know what's going on. As another often-used example, when the baby is picked up by a villain, it will automatically start crying regardless of whether the villain has done something to it or even looks scary. Makes a little more sense in cases where the villain in question is known to eat babies, though not much, given that the baby isn't terribly likely to be aware of that.
- A subtle example in Fullmetal Alchemist (2003); Rose's baby smiles and giggles in the presence of the Elric brothers, but he cries in the presence of Lyra, who for all intents and purposes isn't a threat to either mother or child. But at that point, poor Lyra was actually Dead All Along and the series' Big Bad, Dante, had hijacked her body. She planned to do the same to Rose later, but fortunately didn't succeed.
- In Grimm's Fairy Tale Classics, Princess Elise's baby son in "The Six Swans" starts crying whenever the Hot Witch approaches him. Considering she would later throw him into the forest and make it look like his mother ate him, with only his turned-into-swans uncles' intervention saving him and then his about-to-be-unfairly-executed mother, one can hardly blame the poor kid.
- In Hunter × Hunter, Woble, the infant 14th Prince of Kakin, will cry if someone with ill intent is nearby. Woble will also giggle and stretch her arms out at people who genuinely want to protect her. (Any direct heir to the throne in Kakin is a "Prince," even if female.) This has proven handy multiple times for both Woble and Queen Oito, as Woble and the other princes have been caught in a succession war, the crying helping to determine assassins and other such threats and the giggling to figure out who is truly loyal to Woble and Oito. As such, despite her having been targeted by several of her older brothers and sisters, the two have managed to survive unscathed.
- In Sailor Moon, during the Doom Tree arc, Usagi is helping Mamoru look after a baby boy named Manami. Manami is able to tell that "Natsumi" (En) does not mean well, and as a result, En ends up receiving a Tinkle in the Eye. In some dubs, the baby's train of thoughts is heard and he clearly thinks "I don't like you!" when he's about to piss on her.
- In Issue 19 of Darth Vader: Dark Lord of the Sith, Vader slays the exiled Jedi Master Eeth Koth, who was distracted from their duel when he saw that an Inquisitor had seized his newborn daughter. The Inquisitor handed the crying zabrak baby to the victorious Vader, whose dark presence and stern voice hushed the child with a single command.
- In an issue of the Fantastic Four, Doctor Doom walks the streets of New York in civilian clothes (with a less ornate mask replacing his usual one). He passes a baby boy, who begins screaming and crying uncontrollably. Doom apologizes to the boy's mother for frightening the child; the mother replies that the baby is blind.
- In the Dangerverse's first story, Living with Danger, Remus Lupin thinks this was averted because Harry liked Sirius Black and avoided Peter Pettigrew, when (he thinks) Sirius became a traitor and Peter died fighting him. When he gets told the truth (that the traitor was actually Peter) he realizes that Harry was indeed detecting evil.
- Extremely Nice: Charisse was immediately suspicious of Chloe as soon as she met her (and right she was).
- In the Soul Eater fic The Hand That Rocks The Cradle, Stein and Marie's baby son cries harder when he sees Medusa, and even after she's gotten him to quiet down via Ironic Nursery Tune, he's still visibly afraid of her. Medusa even lampshades the fact that she hasn't done anything to hurt him yet. (Key word: yet.)
- In Megamind, a baby starts crying when it sees one of Megamind's Brain-Bots. Later in the movie, the same baby appears and starts crying when Megamind's Bernard disguise fails and his real self is seen kissing Roxanne. During the climax, after Megamind has seemingly defeated Titan, the same baby appears to start crying, only to stop and look confused like everyone else, lampshading Megamind's HeelFace Turn.
- In Rugrats in Paris, the babies are quick to realize that Coco Labouche is trouble. When Dil meets Coco, he whacks her with his rattle.
Lil: She's not a very nice lady. She's too "pointy."
- In The Blair Witch Project, as a woman holding a baby tells the filmmakers about the legend of the Blair Witch, her baby repeatedly tries to put its hand over her mouth to get her to stop talking. Making this extra creepy is the fact that it wasn't scripted — the child does this of his own volition.
- Inverted in Maleficent. As a baby, Aurora is never afraid of Maleficent and always smiles whenever she is around, even when Maleficent deliberately tries to scare her. In the context of this trope, this is a Foreshadowing that Maleficent still has good in her.
- In Sky High (2005), the parents/superheroes-turned-infants begin to cry when being loaded into an "evil bus". Will's father especially when being spoken to by Royal Pain.
- When a TV news reporter updates on the situation of the soldiers in the first live-action Transformers film, William Lennox's infant daughter becomes fussy right after the report.
- In Stephen King's Revival, Jamie's infant niece takes to him instantly the first time he meets her. When he returns to his brother's house after dealing with Mother, she takes one look at him and starts screaming and thrashing to stay as far away from him as possible. Jamie takes this as evidence that he's been tainted, and distances himself from his family so they won't be marked as well.
- The infant Robert Lockhart in The Vanishing Act of Esme Lennox freaks out at the sight of his uncle James. James is actually his biological father; he raped Esme Lennox, who was thrown into a Bedlam House, and the baby was taken from her and adopted by Esme's sister and James's cousin.
- The third Wayside School book does an interesting variant: the baby doesn't so much detect evil as instantly cure it, as the purely innocent thoughts in its head are too much for the telepathic Child Hater Miss Nogard to bear.
- Subverted in "Silent Witness", an episode of Alfred Hitchcock Presents. The baby cries whenever the man who killed her babysitter comes nearby. His guilty feelings make him suspect that the baby will actually get him caught, and it seems like he's deciding whether to do away with the child too. (He doesn't.) At the end we learn that the baby cries whenever any unknown man comes nearby.
- When Spike is rescuing the baby boy that the Fell Brethren want to make a holy sacrifice in the last epsiode of Angel, the Brethren surround him and order him to put the baby back in the bassinet. He looks at the baby, who shakes his head.
- Baby Wyatt of Charmed tended to put up a blue forcefield if something evil came too close.
- Averted in Game of Thrones. A baby boy giggles happily when the Night's King, the leader of the White Walkers picks him up and turns him into a new White Walker.
- In the Good Luck Charlie episode which shows the Teddy/Spencer break-up, the baby, Charlie, bites Spencer. This is before Teddy discovers he's two-timing her with Skyler. Teddy also dreams that a giant Charlie is attacking Spencer.
- In Malcolm in the Middle, while Lois is pregnant with her fifth child, he starts kicking inside her stomach harder than usual. Lois wonders if something's upsetting him... and then she looks up and sees her racist, manipulative, and all around evil mother Ida at the window.
- Masters of Horror: In the episode "Dreams in the Witch-House", the main guy agrees to babysit his female neighbor's baby while she goes to a job interview. When she suddenly returns to apparently seduce him, it's clear that it's really the witch in disguise because the baby starts loudly crying.
- Death Stranding offers a rare example of this trope not only being justified, but also explicitly taken full advantage of in-universe in the form of Bridge Babies: unborn infants removed from the wombs of braindead mothers and placed inside portable Uterine Replicators, which are used as living warning systems for BRIDGES personnel traveling across the Fallen States of America due to their ability to sense the Beached Things prowling the continent. Main character Sam Bridges carries one throuhout the game, and must rely on it to avoid being caught by the BTs during his deliveries.
- In Mario & Luigi: Partners in Time, Baby Luigi starts crying in the presence of the Cobalt Star's spirit. None of the other members of the party can tell why, but this is one of the hints that the Elder Shroob Princess is sealed inside it.
- In The Legend of Heroes: Trails of Cold Steel III, near the final moments as The Great Twilight is unleashed upon the world, a baby starts crying when it feels the waves of darkness passing through.
- Kevin & Kell: Introduced in January 2021, Leona and Carl's infant daughter Savanna is a lion/rhinoceros with a retractable horn that comes out when she's threatened. Soon after birth, she witnessed Angelique (Kevin's villainous ex-wife) appearing on television... and the horn immediately came out. Leona comments on it:
Leona: "Perceptive judge of character, isn't she?"
- Star Wars Rebels: In the season 2 episode "The Future of the Force", the Inquisitors attempt to abduct two Force-sensitive babies, both of whom start crying when they feel the Inquisitors approaching.
- Tiny Toon Adventures: While Elmyra is more Obliviously Evil, Drooley Davey from the "The Wide World of Elmyra" episode segment of the same name is scared by her presence, seeing her as a Babysitter from Hell. While Elmyra does mean well, she is too young and stupid to be a proper babysitter, and at one point, tries to feed him extremely hot milk. Not helping Davey's case is that his parents pass off his fear of Elmyra as excitement to see her, and that they ask Elmyra to babysit him again the next night.