Oh, they look so sweet and gentle! In M. Night Shyamalan's The Visit, Kathryn Hahn sends her adorable children to visit her beloved parents, and it sounds ideal. The kids have never spent any time with their grandparents, and what better way to get to know them than to travel far out into the countryside, soak up the lovely surroundings, and pass the time relaxing with family members, perhaps helping with a little household cleaning?

As the children soon learn, however, appearances can be deceiving. It's a lesson that younger people have learned to their sorrow in other horror movies, and we're here to offer up a few warning examples.

Thinner (1996)

Distracted while driving, arrogant attorney Billy (Robert John Burke) manages to beat the rap when he runs over and kills an older Gypsy woman. But his freedom is tempered when an old Gypsy man (Michael Constantine) curses him to be thinner, a curse that has dire consequences for Billy. He's not the only one in town to suffer retribution, either.

Cold Sweat (2010)

Two old men in Buenos Aires appear to be harmless, if a little batty. A closer investigation, though, reveals that they are failed political revolutionaries who lure young women into their clutches, and then use nitroglycerine for truly evil purposes. Oh, and then there are the boxes of dynamite they keep for no good reason.

The Skeleton Key (2005)

Kate Hudson becomes a personal care assistant for the disabled John Hurt, whose wife Gena Rowlands is immediately suspicious of the younger woman. The mystery of the older woman's possibly homicidal impulses will eventually reveal an even more dangerous source of trouble.

Phantasm (1979)

An older, very creepy mortician in California, known as the Tall Man, lives up to his shadowy reputation, and then some.

Rosemary's Baby (1968)

A young housewife (Mia Farrow) is a bit adrift when she moves into an old Manhattan apartment building with her husband (John Cassavetes), but her new neighbors prove to be quite welcoming, especially the very sweet and kind Minnie (Ruth Gordon). The neighbors have a diabolical reason for their inviting attitude, however.