William Weir
William Weir may refer to:
- William Alexander Weir, Quebec lawyer and politician
- William Weir (architect), Scottish restorer of historic buildings
- William Weir, 1st Viscount Weir, Scottish industrialist
- William Weir, 3rd Viscount Weir, British peer and businessman
- William Gilbert Weir, Canadian politician
- Bill Weir, co-anchor of Good Morning America Weekend Edition
- Bill Weir (footballer), Australian rules footballer
- William Weir (aviator), World War I flying ace
- William Weir (trade unionist), British coal miner and politician
- Dr. William Weir, fictional character in Event Horizon (film)