Casimir I may refer to:
- Casimir I of Poland (1016–1058), duke of Poland
- Casimir I, Duke of Pomerania (after 1130 – 1180), duke of Pomerania-Demmin
- Casimir I, Duke of Cieszyn (1280/90 – 1358)
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Casimir I
42 words updated Jun 20, 2026, 1:05 AM