| Simon I de Montfort | |
| Seigneur of Montfort | |
| Reign: | 1053–1087 |
| Predecessor: | Amaury I de Montfort |
| Successor: | Amaury II de Montfort |
| Noble Family: | House of Montfort |
| Father: | Amaury I de Montfort |
| Mother: | Bertrade |
| Issue: | |
| Spouse: | Isabel de Broyes Agnes d'Evreux |
| Birth Date: | 1025 |
| Birth Place: | Montfort l'Amaury, Kingdom of France |
| Burial Place: | Épernon, Kingdom of France |
Simon I of Montfort or Simon de Montfort (– 25 September 1087) was a French nobleman. He was born in Montfort l'Amaury, near Paris, and became its lord. He was the son of Amaury I de Montfort and Bertrade. At his death he was buried about away in Épernon, because it was the site of the fortress he was instrumental in constructing.
Simon I first married Isabel de Broyes (b. 1034 in Broyes, Marne), daughter of Hugh Bardoul. Their children were:
Simon I's second marriage was to Agnes d'Évreux (b. 1030), daughter of Richard, Count of Évreux. Their children were: