Give a stream of consciousness and then the final answer. Jaime Murray (born 21 July 1976) is an English actress, known for playing Stacie Monroe in the BBC series Hustle and Lila West in the Showtime series Dexter. She is also known for her recurring roles as Gaia in the Starz miniseries Spartacus: Gods of the Arena, as Olivia Charles in The CW series Ringer, as Helena G. Wells in the Syfy series Warehouse 13, as Stahma Tarr in the Syfy series Defiance, and as the Black Fairy in Once Upon a Time.

Based on this passage, who plays the dark fairy on once upon a time?
To answer the question, consider the following: She is also known for her recurring roles as Gaia in the Starz miniseries Spartacus: Gods of the Arena, as Olivia Charles in The CW series Ringer, as Helena G. Wells in the Syfy series Warehouse 13, as Stahma Tarr in the Syfy series Defiance, and as the Black Fairy in Once Upon a Time.
So, the final answer is Jaime Murray.