William Cox (19 December 1764 – 15 March 1837) was an English soldier, known as an explorer, road builder and pioneer in the early period of British settlement of Australia.

Cox used his influence so that the prisoners were often allowed up on deck for fresh air, and Holt in his memoirs states that as a result "the ship was the healthiest and best regulated which had ever reached the colony".

[1] The Dictionary of Australian Biography records that Cox was cleared in 1808, and was promoted to Captain of 102nd Regiment of Foot, and placed in charge of Irish political prisoners.

In 1814, Governor Lachlan Macquarie approved Cox's 'voluntary offer of your superintending and directing the working party' that would build a road crossing the Blue Mountains, between Sydney and Bathurst.

The completed dirt track was 12 feet (3.7 m) wide by 101+1⁄2 miles (163.3 km) long, built between 18 July 1814 to 14 January 1815 using five free men, 30 convict labourers and eight soldiers.

As landowner, magistrate and commander of the Windsor Garrison, William Cox organised punitive & dispersive expeditions from July 1816 along the Nepean–Hawkesbury River in which he 'reported' the killings of four Aboriginal men.

In response to ongoing Aboriginal resistance to settlers, Cox had sent Governor Lachlan Macquarie a grim manifesto for a final showdown on the Hawkesbury-Nepean.

Three detachments of soldiers, each with a constable who knew the area, and a 'friendly native' as a guide, were to be posted at the Grose River, Windsor and downriver at Portland Head respectively.

The BBC One television programme Who Do You Think You Are?, which aired on 30 August 2010, traced the ancestry of Australian soap and pop star Jason Donovan through his mother Sue Menlove's side of the family back to William Cox.