Sienna Julia Marie Holmes is an american opposum living in Blumenfelder. She is the daughter of Kitty & Julian Holmes, the younger sister of Joshua Holmes, the twin sister of Wynn Holmes, and the older sister to Joseph Holmes II.

She is also the wife of Milan Montague, and the mother of Josiah, Lenora, and Fiske Holmes.

A devoted wife, mother, and politician; Sienna has a smile that can light a room. She works as a trusted advisor—and best friend—to the King, Clifford Squash.