Sir William Leighton (1752 – 23 April 1826) was a British shipowner and merchant who served as the Lord Mayor of London in 1806.^[1]

Leighton's family was from County Durham in the North East of England and he moved to London around 1779 following his father's death.^[2] Leighton worked as a coal merchant shipping coal from the port of Newcastle, and was based at Newcastle's Coal Exchange.^[2]

Leighton was a prominent shipowner who owned Borrowdale, Fishburn and Golden Grove, three of the ships of the First Fleet, which transported convicts to the British colony of New south Wales.^[3] Leighton also owned several ships that were sent as military transports to the British Province of Quebec with contracts from the British Navy.^[2]

Because of his maritime interests, Leighton served on various shipping committees.^[2]

Leighton was a member of the Livery company of the Worshipful Company of Wheelwrights.^[4] He was created an alderman in the City of London's Billingsgate ward in 1799, before his resignation as an alderman in 1821.^[1] He was subsequently elected one of the Sheriffs of the City of London in 1803.^[1]

In 1806, Leighton was proclaimed Lord Mayor of London, and knighted on 1 May that year.^[1] Leighton was listed as one of the governors of Christ's Hospital in 1825.^[5]

Leighton died at Kemnal House in Kent, in 1826.^[1] He had previously lived in Charlton.