Evil Orphan

Sometimes you get lucky, and the Mysterious Waif you adopted becomes a well-adjusted and welcome addition to the family. Other times. . .not so much.

Of course, the young couple has no idea anything is wrong, but tropers will know right away there's something not right with this newcomer. She's a Creepy Child, who looks like she strolled straight out of the Uncanny Valley. It's not long before things start going wrong around her. Pets start acting up. Things go missing. There are fires. Injuries. Nocturnal birds of prey show up everywhere.

As if they don't have enough to worry about, the couple's biological child is making up crazy stories about how the orphan is planning to kill them all in their sleep! They will be ignored. Sometimes one or both of the parents figure it out at the very last minute. Sometimes it falls to the children to stop her.

Feminine pronouns are used because Evil Orphans are most times little girls but evil little boys are hardly uncommon.

The Evil Orphan is the modern-day incarnation of the changeling tale. It uses the tried-and-true horror of Subverted Innocence and the Devil in Plain Sight, as there is little that can compare to the fear and revulsion of discovering that one has been succoring evil incarnate in ones own home.

Expect anything of the Ungrateful Bastard, but be particularly on the lookout for those that play on her youth, like the Wounded Gazelle Gambit. May cause Fridge Horror when the audience wonders just how she became an orphan in the first place. Incorporates any and every trope having to do with with Creepy Children. See also Enfant Terrible.

The polar opposite of the Heartwarming Orphan.

Anime

 * Johan from Monster, of course.
 * from Ashita no Nadja didn't start as this, but she got in the role very quickly after
 * While Orochimaru of Naruto didn't defect from Konoha until around 10 years before the start of the story, the Third Hokage noticed there was something unsettling about it, but largely turned a blind eye to it because of his talent.
 * Mukuro from Katekyo Hitman Reborn is adopted by another family but soon uses the man taking care of him to kill off the entire family.

Film

 * The Ring: Samara Morgan, oh so very much.
 * Orphan: Yeah. That one.
 * In fact.
 * Subverted in The Good Son: the evil one is the kid with both parents, but he manipulates the people around to make it look like his innocent, half-orphaned cousin is the bad seed.
 * The Omen. The boy Damien is an orphan substituted for the couple's real child, who died shortly after birth.
 * The title character of Mikey.

Literature

 * The novel Hogfather features Mr. Teatime, who was taken in by the Assassin's Guild after both his parents died suddenly when he was very young. In the words of guildmaster Lord Downey, "In hindsight, perhaps we should have looked into that a bit more."
 * Harry Potter: Lord Voldemort was raised in a Muggle orphanage, where he apparently spent his free time bullying the other children in a variety of cruel and magical ways. Harry, of course, is an aversion, as is in the last book.
 * Voldemort is something of an odd case, as he's only an orphan because.
 * Heathcliff in Wuthering Heights. His Freudian Excuse is relatively strong, but at any rate, he ends up a usurping beast of pure spite, and his intentions are just that.

Live Action TV

 * CSI has the very Creepy Insufferable Genius Hannah, whose parents have died (the details are never explained) by her second appearance. . She also Hannibal Lectures Sara, possibly contributing to her decision to go on a vacation to the rainforest.
 * Supernatural has a young girl in the first season who not only cut the throats of her biological and adoptive families, but made it look like her adoptive father did it. Then she did it to people who owned a painting of her adoptive family.
 * Considering how ugly that painting was...And that they knew it has a bad reputation of previously deceased owners...Maybe they had it coming.
 * Alexander on Smallville is an infant clone of Lex Luthor. Tess Mercer hoped that by raising him to be good, she could save him from the Luthor legacy. Unfortunately, Alexander has all of Lex's memories, and is aging very rapidly to boot. As of "Luthor" he's gone AWOL, and is out there, somewhere, plotting revenge on her and Clark.

Video Games

 * During a questline in World of Warcraft Alliance players encounter Hope Saldean, a friendly young lady who was adopted by the Saldean couple four years earlier. While Hope seemingly spends much of the Westfall-storyline feeding the homeless, a shadowy figure is gathering the old members of the Defias Brotherhood. In the end Hope reveals herself to be, who has been secretly plotting against the Kingdom of Stormwind the whole time.
 * Whole bunch of them in Rule of Rose, though all have their own Freudian Excuse, and you will end up feeling more pity than loathing for them by the end.
 * in Professor Layton and the Unwound Future, who lost his parents in 10 years ago, and schemed to take vengeance on the people responsible with the money he inherited from his adoptive mother.