William is a male rabbit character initially portrayed as an unseen romantic interest of Stella, a rabbit who designs dresses. For a substantial period, his appearances remained partially obscured, with only his arms, ears, hands, and feet visible during encounters with Stella. This visual mystery positioned William as a hidden figure central to a subplot involving Stella's affections.

The narrative later resolved this obscurity in a specific second-season episode of the animated shorts, fully revealing William's appearance and formally identifying him as William Cinnamon. This revelation solidified his physical characteristics and role within the Sylvanian universe.

William's existence and confirmed identity enhance the depiction of relationships and social dynamics among rabbit families and the wider Sylvanian community. His connection to Stella—alternately known as Bell or Freya across regional dubs—places him within the Periwinkle or Chocolate Rabbit family lineage.