Robert I may refer to:

• Robert I of France (865-923), king of the Franks
• Robert I of Scotland (1274-1329), usually known as Robert the Bruce
• Robert I of Naples
• Robert I of Dreux
• Robert I of Poitiers
• Robert I, Count of Flanders, known as Robert the Frisian
• Robert I, Duke of Burgundy (1011 – 1076)
• Robert the Magnificent (c. 1000 - 1035), Duke of Normandy