William Joseph O'Connor (4 May 1862 –23 November 1892) was a professional oarsman who attempted to win the World Sculling Championship.
In 1885 they repeated as CAAO champions and O'Connor won the single with the tactic that would become his trade mark, a rapid, explosive stroke at the start.
These successes and reports of heavy wagering on them brought charges of professionalism against O'Connor and Enright.
Exonerated by the CAAO, they were declared ineligible by the NAAO and so turned professional, staked by Toronto businessman Joseph Rogers.
In only his second match race he had to row alone when prominent professional Wallace Ross of Saint John, New Brunswick, backed out at the last moment rather than be beaten by one "just out of the amateur ranks."
After that, he continued to win regattas with such ease that, except for one defence against fellow Canadian Jake Gaudaur Snr.
But O'Connor could not bring the World Sculling Championship, lost by Hanlan in 1884, back to Toronto.
On 9 September 1889 on the historic Putney to Mortlake Championship Course on the Thames in London, England, he lost his challenge to the world champion, Henry Ernest Searle of Australia.
O'Connor was so unhappy with the result and attempted to prevent the payment of the stakes to Stanbury who then offered to row the race again.
In 1890 O'Connor took over the Sherman House in Toronto, the saloon of his brother, John J., who died unexpectedly in October.
In August 1891 O'Connor and Ned Hanlan won the world championship in the double sculls before 30,000 spectators at Burlington Beach.