A number of famous people in history were named William:
- King William I of England (William the Conqueror, William the Bastard)
- King William II of England
- King William III of England
- Emperor William I of Germany
- Emperor William II of Germany
- Count William of Holland
- King William I of the Netherlands
- King William II of the Netherlands
- King William III of the Netherlands
- Prince William I of Orange (William the Silent)
- Prince William II of Orange
- Prince William III of Orange
- Prince William IV of Orange
- Prince William V of Orange
- Count William of Poitiers
- King William I of Scotland (William the Lion)
- King William II of Scotland
- King William I of Sicily
- King William II of Sicily
- King William III of Sicily
- King William IV of the United Kingdom
- Prince William of Wales
- William de Corbeil, English Bishop
- William of Mainz, German Bishop
- William of Malmesbury, English Historian
- William of Ockham, English Monastic
- William de la Pole, English Nobleman
- William of St Carilef, English Bishop
- William Shakespeare, English Playwright
- William of Tyre, Bishop in the Holy Land
- William of Wied, German Nobleman
- William of Wykeham, English Bishop
- William Brown, hero of a book series by Richmal Crompton
