A crane fly is an insect in the family Tipulidae. Adults are very slender, long-legged flies that may vary in length from 2–60 millimetres (0.079–2.4 in) though tropical species may exceed to 100 millimetres or 3.9 inches.

In the United Kingdom, Ireland, Newfoundland and Nova Scotia they are commonly referred to as daddy longlegs, but this name can also refer to two unrelated arthropods: members of the arachnid order Opiliones (especially in the United States and Canada) and the cellar spider Pholcidae (especially in Australia). The larva of the European Crane Fly is commonly known as a leatherjacket. These larvae can cause damage to lawns by feeding on the roots of grass plants.

Numerous other common names have been applied to the crane fly, many of them more or less regional, including mosquito hawk, mosquito wolf, mosquito eater (or skeeter eater), soldier , gallon-nipper, and gollywhopper.

At least 4,256 species of crane flies have been described, most of them (75%) by the specialist Charles Paul Alexander. This makes Tipulidae one of the largest families of Diptera (although smaller than Limoniidae, one of the other extant families of crane flies).