Niccolò I may refer to:
- Niccolò I d'Este, Marquis of Modena and Ferrara (died 1344), see Duke of Ferrara and of Modena
- Niccolò I Ludovisi (1634–1664)
- Niccolò I Sanudo (died in 1341)
- Niccolò I Trinci (died in 1421)
See also
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