William Collins, Sons & Co., often referred to as Collins, was a Scottish printing and publishing company founded by a Presbyterian schoolmaster, William Collins, in Glasgow in 1819, in partnership with Charles Chalmers, the younger brother of Thomas Chalmers, the minister of Tron Church in Glasgow.

Collins merged with Harper & Row in 1990, forming a new publisher named HarperCollins.

The firm published its first dictionary, Greek and English Lexicon, in 1824. The company had to overcome many early obstacles, and Charles Chalmers left the business in 1825. The first series of Collins Illustrated Dictionaries appeared in 1840, including the Sixpenny Pocket Pronouncing Dictionary, which sold approximately 1 million copies. By 1841 Collins was established as a printer of Bibles. In 1846, Collins retired and his son Sir William Collins took over.

In 1848, the firm developed as a publishing venture, specialising in religious and educational books. In 1856, the first Collins atlas was published. The company was renamed William Collins, Sons and Co Ltd. in 1868. (The Library of Congress reports W. Collins & Co., or William Collins & Company, Collins & Co., etc., before "sometime in the 1860s", then "William Collins Sons and Co.")

Although the early emphasis of the company had been on religion and education, Collins also published more widely. In 1917, with Sir Godfrey Collins in charge, the firm started publishing fiction. Collins Crime Club (1930–94) published all but the first six of Agatha Christie's novels, starting in 1926, as well as the British editions of Rex Stout's Nero Wolfe books and many others from the Golden Age of Detective Fiction. Upon purchasing the rights to the works of C. S. Lewis, Fount was established as Collins's religion imprint.

Between 1941 and 1949, Collins published Britain in Pictures, a series of social history books which were designed to boost morale during the Second World War. Authors included George Orwell, John Piper, Neville Cardus, Cecil Beaton, Vita Sackville-West, David Low, Francis Meynell, Edith Sitwell, Graham Greene and John Betjeman.

Collins ultimately became a diverse and prolific company, publishing a wide range of titles, including many aimed at a juvenile audience, such as the books of Dr. Seuss (in the Commonwealth) and Racey Helps in the 1950s. Collins founded its New Naturalist series of nature books relevant to the British Isles in 1945, with Butterflies by E. B. Ford. Three volumes appeared in the summer of 2015.

In 1953, Collins launched its Fontana Books series. Later Fontana Books became a Collins imprint complete with its own series, including the Fontana Monarchs, the Fontana African Fiction series and, from 1970, the Fontana Modern Masters, a series of pocket guides to influential writers, philosophers and other thinkers and theorists of the twentieth century. Other William Collins, Sons, imprints included Fontana Lions and Fontana Young Lions, which published books for children and teenagers, and Grafton Books.