Renier I of Montferrat (1084-c. 1136) was marquess of Montferrat from around 1100 to around 1136. He was the son of marquess and his wife Otta d'Aglie, a daughter of Tibaldo d'Aglie.

Renier married Gisela, daughter of William I, Count of Burgundy. Gisela was the widow of Humbert II of Savoy, who had died in 1103, and by whom she was mother of Adelasia of Moriana (fr. Adélaide de Maurienne), who in 1115 became the second queen of Louis VI of France. She and Renier had three or four daughters:

• Johanna, who married William Clito, Count of Flanders in 1127, and was widowed a year later.
• Matilda, who married , .
• Name unknown (possibly Isabella), who married (although it is possible that this may be a second marriage of Johanna).
• Adelasia, who became a nun.

They also had one son, William, who succeeded his father.

Sources

• Usseglio, Leopoldo. I Marchesi di Monferrato in Italia ed in Oriente durante i secoli XII e XIII, 1926.