William Montagu
William Montagu may refer to:
- William Montagu, 2nd Baron Montagu, English peer, soldier and courtier
- William Montagu, 1st Earl of Salisbury, English nobleman
- William de Montagu, 2nd Earl of Salisbury
- William Montagu, 2nd Duke of Manchester
- William Montagu, 5th Duke of Manchester, British peer, soldier, colonial administrator and politician
- William Montagu, 7th Duke of Manchester, British peer and Member of Parliament
- William Montagu, 9th Duke of Manchester, British peer and politician
- William Montagu, English MP for Midhurst and Stockbridge, imprisoned for debt
- William Montagu (judge), British judge
- William Montagu (MP), British politician for Huntingdonshire and Bossiney
- William Augustus Montagu, British military officer
- William Augustus Montagu (MP), British politician
- William Montagu Manning, Australian politician