Sir William John Clarke, 1st Baronet (31 March 1831 – 15 May 1897), was an Australian businessman and philanthropist in the Colony of Victoria.

For the next ten years he resided in Tasmania, working the Norton-Mandeville estate in conjunction with his brother, Joseph Clarke.

His largest gifts were £10,000 for the building fund of St Paul's cathedral and £7000 for Trinity College, Melbourne University.

[4] For many years Clarke bore the full expense of the Rupertswood battery of horse artillery at Sunbury, Victoria.

In 1886, he was a member of the Victorian commission to the Colonial and Indian exhibition, and in the same year Cambridge gave him the honorary degree of LL.D.

In Clarke's later years, although his interests lay principally in the country, he lived at his town house Cliveden in East Melbourne.

He divided one of his estates into small holdings and was a model landlord, and he showed much foresight in allying science with agriculture by employing MacIvor as a lecturer.

His second wife, Janet, who had been associated with him in philanthropic movements, kept up her interest in them, especially in all matters relating to women, until her death on 28 April 1909.

[citation needed] His second son, Ernest Edward Dowling Clarke (1869–1941), was a noted racehorse owner, closely associated with trainer James Scobie.