William Gardiner was an Irish international rugby union player.
A native of County Armagh, Gardiner was a North of Ireland three-quarter, capped 17 times for Ireland in the 1890s. He appeared in the 1894 triple crown-winning team and held the captaincy for his final match against Wales in 1898.
Gardiner's nephew James Gardiner was capped for Ireland.
Married with three children, Gardiner was a weaving company director and died of a stroke in 1924.