A can opener (in North American English and Australian English) or tin opener (used in British English) is a mechanical device used to open tin cans (metal cans). Although preservation of food using tin cans had been practiced since at least 1772 in the Netherlands, the first can openers were not patented until 1855 in England and 1858 in the United States. These early openers were basically variations of a knife, though the 1855 design continues to be produced. The first can opener, consisting of the now familiar sharp rotating cutting wheel that runs round the can's rim to cut open the lid, was invented in 1870, but was considered very difficult to operate for the ordinary consumer. A successful design came out in 1925 when a second, serrated wheel was added to hold the cutting wheel on the rim of the can. This easy-to-use design has become one of the most popular can opener models.

Around the time of World War II, several can openers were developed for military use, such as the American P-38 and P-51. These featured a robust and compact design with a pull cutting blade hinged to a corrugated handle with a pivot. Electric can openers were introduced in the late 1950s and met with success. The development of new can opener types continues with a recent redesign of a side-cutting model.