William Henry Appleton (January 27, 1814 – October 19, 1899) was an American publisher, eldest son and successor of Daniel Appleton.
He was born at Haverhill, Massachusetts on January 27, 1814. Appleton began his career in publishing in 1838. He married Mary Moody Worthen in 1844.
In 1848 he became the senior member of the firm of D. Appleton & Company, in partnership with his brother John Adams Appleton; they were joined in partnership by three younger brothers. William became the firm's London representative in 1853. He was active in the struggle for an international copyright, and served a term as president of the American Publishers Copyright League. His firm published works by a range of noteworthy authors, including Hall Caine, Lewis Carroll, Arthur Conan Doyle, Charles Darwin, Thomas Henry Huxley, Herbert Spencer, and John Stuart Mill, as well as leading American scientists and philosophers of his era.
Among the reference books brought out by him were The New American Cyclopædia (1858–63); Webster's Spelling Book; Appletons' Cyclopædia of American Biography (1887–1900), Applied Mechanics (1897), and an Annual Cyclopœdia (1885–1903). He wrote Letters on International Copyright (1872).
Appleton was a prominent figure in publishing for a period of sixty years. He lived at Wave Hill (New York); the house was later turned into a botanical garden in the Riverdale section of The Bronx, New York.