Tricia Janine Helfer (born April 11, 1974) is a Canadian and American actress. She is known for portraying Number Six in the science fiction series Battlestar Galactica (2004–2009). She also voiced Sarah Kerrigan in the video game StarCraft II and its expansion packs (2010–2015), and portrayed Charlotte Richards/Goddess in the urban fantasy series Lucifer (2016–2021).