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 I of Holland
- Count William II of Holland
- Count William III of Holland
- Count William IV of Holland
- Count William V of Holland
- Count William VI 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