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| Boniface I | |
|---|---|
 Boniface elected as leader of the Fourth Crusade, Soissons, 1201: history painting by Henri Decaisne, early 1840s, Salles des Croisades, Versailles. | |
| Marquis of Montferrat | |
| Reign | 1192 – 4 September 1207 |
| Predecessor | Conrad of Montferrat |
| Successor | William VI, Marquis of Montferrat |
| King of Thessalonica | |
| Reign | 1205 – 4 September 1207 |
| Successor | Demetrius of Montferrat |
| Born | c. 1150 |
| Died | 4 September 1207 (aged c. 57) |
| Spouse | Helena del Bosco Margaret of Hungary |
| Issue | William VI, Marquis of Montferrat Beatrice of Montferrat Agnes of Montferrat Demetrius of Montferrat |
| House | Aleramici |
| Father | William V, Marquis of Montferrat |
| Mother | Judith of Babenberg |
Boniface I, usually known as Boniface of Montferrat (Italian: Bonifacio del Monferrato; Greek: Βονιφάτιος Μομφερρατικός, Vonifatios Momferratikos) (c. 1150 – 4 September 1207), was the ninth Marquis of Montferrat (from 1192), a leader of the Fourth Crusade (1201–04) and the king of Thessalonica (from 1205).