William Chandless (7 November 1829[1]–5 May 1896)[2] was an English explorer of the Amazon Basin in the 1860s.

During his time in the Amazon he lived in Manaus (now the capital of Brazil's Amazonas state) from where he explored many of the Amazon River's southern tributaries and contacted various indigenous tribes.

Chandless sent reports of his expeditions to the Royal Geographical Society, which published them in its journal.

In 1866, following his survey of the Purus River, the Society awarded him its Patron's Medal.

Recently, in 2003, a protected area on Brazil's border with Peru, Chandless State Park, was named in his honour.