From Halopedia, the Halo wiki
Tricia Janine Helfer (born April 11, 1974) is a Canadian actress and model, best known as Number Six in Battlestar Galactica.
In Halo 3: ODST, she voices Naval Intelligence Captain Veronica Dare, who is also modeled after Helfer's likeness.
Tricia Helfer and Nathan Fillion recording lines for Halo 3: ODST.
Veronica Dare, modeled after Tricia Helfer.