This trope commonly consists of a scene being well under way when the audience becomes aware of an entity or object being in the scene, and they were unaware of it beforehand.
Usually the object or entity is in the background and moves to the foreground, but there are plenty of other ways for it to happen. Often times the awareness is created by movement, but can also be from lighting or a different camera angle. The awareness is also commonly made through a sudden Jump Scare, although many times it can be a slow reveal.
A more specific and closely related trope is The Calls Are Coming from Inside the House.
- Alien: On at least two separate occasions, the Xenomorph turns out to be Hidden in Plain Sight, camouflaged by crouching against a wall or in a dark corner and looking like a piece of set-dressing.
- In The Gallows, there is a scene where the hangman moves forward from the dark background and drags the girl in the scene into the background. Coincidentally, he does this via the Ankle Drag trope. Bonus fact: This scene appears on the poster on the film's IMDb page.
- Indiana Jones and the Temple of Doom has a well-done example during an otherwise light-hearted scene of he and Willie both debating to themselves about whether to resolve their sexual tension. We see a mural of a shadowy figure painted in the background whenever it cuts to Indy in closeup, but don't pay it any mind until the "figure" in the painting quietly sneaks up from behind and tries to garrote him.
- In The Snorkel, the killer is revealed to have been under the floorboards the entire time.
- Simon Ark: In "The Vicar of Hell", Simon and his companions are searching for a surviving copy of a book which had been banned as blasphemous and all known copies destroyed. Although they cannot find it in the place where they have been told it is, Simon tells them its been here all along, and they have been staring at it. It is literally on the walls. In Tudor times, destroyed books were not necessarily burned. They were sometimes flocked and turned into wallpaper. The odd patterns on the wallpaper that had been commented on earlier were actually the remains of the book's illustrations that were still visible.
- The shapeshifting creature in Red Dwarf that acts as a vampire on emotional energy is there in the galley on the Dwarf, but is only noticed when Kryten realises there's one kebab too many on Lister's plate. The extra one is of course the emotion-eating monster.
- In the Five Nights at Freddy's franchise, there are several camera angles where the animatronics are in the background and can go unnoticed due to the lack of proper lighting, in line with the theme of the game.
- In a Five Nights at Freddy's 3 video posted by Let's Play, Gavin experiences it firsthand when Springtrap is partly present in the doorway, and loudly yells that Springtrap was there the whole time.