The Wellington boot, also known as a welly, a wellie, or a gumboot, is a type of boot based upon Hessian boots worn and popularised by Arthur Wellesley, 1st Duke of Wellington and fashionable among the British aristocracy in the early 19th century. The boot is waterproof and is most often made from rubber or a synthetic equivalent though in its origins it was made of leather. It is usually worn when walking on very wet or muddy ground, or to protect the wearer from industrial chemicals.

In Britain, there is a light-hearted sport, known as wellie wanging, which involves the throwing of Wellington boots as far as possible. The boots are also popular fetish items among many people.

The boot has also given its name to the welly boot dance, said to have been performed by miners in Africa to keep their spirits up whilst working. In the 1970s, Scottish comedian Billy Connolly adopted a comical ode to the boot called "The Welly Boot Song" as his theme tune and it became one of his best-known songs.

Wellington boots, though invented in Britain, are very popular in Canada, particularly in springtime, when melting snows leave wet and muddy ground for a couple of months. Children can be seen wearing them to school and taking them to Summer camps.

Green Wellingtons are most popular in Britain, while black Wellingtons, particularly with red or green soles, remain the favourite of Canadians. Yellow-soled black Wellingtons are often seen in the US, in addition to Canadian styles. Wellingtons specifically made for cold weather, lined with warm insulating material, are especially popular during Canadian winters.

See also: Mackintosh, Rubber fetishism, Gumboot Day