Sierra was a female active for the Los Angeles Dollhouse who was noted by Joe Hearn that she "got the job done." Sierra went on a final engagement prior to Priya Tsetsang joining the Dollhouse with the same designation prior to, or in conjunction with her departure from the L.A Dollhouse. (S1: "Stage Fright"; S2: "Belonging")
This Sierra has made no onscreen appearances, but has been referenced to in "Stage Fright" and "Belonging", making her an unseen character. Her final fate has not been explicitly explained, but it is implied that she may have simply served a full contract or that she went on a permanent engagement. It is also possible that she may have died, but given the nature of the discussion between Adelle DeWitt and Topher Brink and Joe Hearn's reaction to Topher, it is likely that this is not one of the scenarios.