William Cox (1817 – 12 December 1889) was a British solicitor and Liberal Party politician.

Cox qualified as a solicitor in 1840 and became a member of the Common Council of the City of London in 1851.^[1] In 1857 he was chosen as a candidate to contest the two-seat constituency of Finsbury as a Whig and supporter of the policy of Lord Palmerston.^[2] The election was held on 29 March, and Cox was elected, coming second of the four candidates, with a majority of 156 votes over the third-placed candidate.^[3]

When a further general election was called in 1859, Cox found himself opposed by two other Liberal candidates. He lost his seat, with The Standard noting satirically that:

"...the honourable gentleman neither spared his lungs nor his powers of sitting out the most long-winded debate... He had almost arrived at the distinction of being called a bore... Happily for his peace, his health, and his pocket, his too Liberal career has been stopped by an oblivious constituency".^[4]

On 13 November 1861 one of the sitting members of parliament for Finsbury, Thomas Slingsby Duncombe, died.^[5] On 9 December Cox announced that he would seek election in the resulting by-election.^[6] The by-election was held on 16 December, and Cox defeated his only opponent, J R Mills by 42 votes.^[7]

Cox held the seat until the next general election in July 1865. He was one of four Liberal candidates who, along with a lone Conservative, contested the seat.^[8] He failed to be re-elected, finishing in third place with 5,008 votes, more than 2,800 behind the second-placed candidate.^[9]

Between c.1861 and c.1868 Cox commissioned a house to be built in the village of Netteswell, Essex.^[10] The house was called 'Spurriers'. Cox lived in the house until his death in December 1889 aged 72.^[11][12] William Cox is buried in the parish of St Andrew's churchyard, Netteswell, Harlow.