In the Enchanted Forest, Gus was a mouse who lived in Cinderella's pantry and ate cheese. When Lady Tremaine locks Cinderella away so that Prince Thomas won't be able to find her, Gus is the one who catches Snow White's attention and leads them to Cinderella.
When the first Dark Curse hits, he gains human form and becomes Billy, a mechanic in Storybrooke.
After the curse breaks, he wants to get to know Ruby more, but she is unsure of herself. The next morning, he shows up dead, having been chopped in half. Ruby thinks that she may have done it while in wolf form, until George is revealed to be responsible for it.
- None known (family)
- He is based on one of Cinderella's mouse friends in the fairytale Cinderella.
- S1, E04: "The Price of Gold"
- S1, E05: "That Still Small Voice"
- S1, E19: "The Return"
- S2, E07: "Child of the Moon"
- S2, E17: "Welcome to Storybrooke" (flashback)
- S6, E03: "The Other Shoe" (flashback)
- Bk 1: "Reawakened"