A Wendy house is a United Kingdom term for a playhouse for children, which is large enough for one or more children to enter. Size and solidity can vary from a plastic kit to something resembling a real house in a child's size. Usually there is one room, a doorway with a window on either side, and little or no furniture other than that which the children improvise.

The original was built for Wendy Darling in J. M. Barrie's play, Peter Pan, or The Boy Who Wouldn't Grow Up. Wendy was shot by the Lost Boy Tootles after arriving in Neverland, so Peter Pan and the Lost Boys built a small house around her where she had fallen. It was inspired by the wash-house behind Barrie's childhood home in Kirriemuir and first appeared in story form in The Little White Bird in which fairies build a house around Mamie Mannering—the prototype for Wendy—so protecting her from the cold.

A prop house was created by Barrie for the first stage production of the play in 1904. It was constructed like a tent so that it could be erected quickly during a song which Wendy starts with:

I wish I had a darling house
The littlest ever seen,
With funny little red walls
And roof of mossy green.

John's hat was used as a chimney and a slipper was used as a door knocker. Toy manufacturers soon created replicas of the stage Wendy house, which have become a standard toy found in British gardens ever since.