William Penn Brown (1841–1929), of New York City, was an early pioneer in the hobby of stamp collecting.

Brown was born in India of missionary parents and was raised in Japan before he came to the United States and started a successful business selling stamps in New York City in 1860.

In 1864 Brown was the editor of the London and New York Stamp Collectors Review, the first journal for American philatelists.

He also published, in 1970, a catalog entitled The Curiosity Cabinet, which contained the first listing of United States locals, including his account of finding the New Haven postmaster provisional.

William Brown was named to the American Philatelic Society Hall of Fame in 2008.