William I of Geneva (ca. 1132 – 25 July 1195) was Count of Geneva from 1178 to 1195, in succession to his father, Count Amadeus I of Geneva. William's mother was Amadeus' wife, Matilda de Cuiseaux.
Marguerite of Geneva, wife of Thomas I of SavoyIn 1195 William was escorting his daughter Marguerite to France for her intended wedding to King Philip II. Thomas of Savoy ambushed the party, carried off Marguerite and married her himself, producing some eight sons and six daughters.