William Yarrell (June 3, 1784 - September 1, 1856) was an English bookseller and naturalist.

Yarrell is best known as the author of The History of British Fishes (2 vols., 1836) and The History of British Birds (2 vols., 1843). The latter went into several editions and was the standard reference work for a generation of British ornithologists. He was also the first person to describe the Bewick's Swan in 1830, distinguishing it from the larger Whooper Swan.

Yarrell was born in central London. His father was a newsagent, and he succeeded to the business, continuing it until a few years before his death. He acquired the reputation of being the best shot and the best angler in London, and soon also became an expert naturalist. In 1825 he was elected a fellow of the Linnean Society, of which he subsequently became treasurer, and was a diligent contributor to their Transactions; and he was one of the original members of the Zoological Society of London. He died during a trip to Great Yarmouth and a memorial was later erected in St James Church, Piccadilly.

Yarrell has a number of species named after him, including the birds Yellow faced Siskin Carduelis yarrellii and Chilean Woodstar Eulidia yarrellii and the fish Yarrell's Blenny. The British sub-species of the White Wagtail, the Pied Wagtail Motacilla alba yarrellii, was also named for him.