Black Swan

The Black Swan is a character who first appears in "UnmAsked." Spencer finds the sketches for Black Swan's costume in "A's" lair, and Aria, Emily, and Hanna spot her at the Masquerade Ball. Her identity was unknown until it was revealed in "Birds of a Feather" that it was Ashley Marin. Before Mona disclosed to Spencer that she was "A," Spencer, Hanna, Emily, and Aria believed Black Swan may have been "A."

Black Swan is seen talking to Lucas and Jenna at the Masquerade Ball. When the Liars try to confront her she runs away from them.

Physical Appearance
Black Swan has dark hair, fair skin, and is described by Hanna as being tall and having a size two frame. She is seen wearing a costume similar to that of Odile in the ballet "Swan Lake." She wears a mask, which conceals her identity.

The Identity of the Black Swan
In the episode "Birds of a Feather " it is revealed that  Ashley is the Black Swan and that the night of the Masquerade Ball she received a note, blackmailing her to wear the costume to the ball. The note also said that she had to distract Jenna, which is why the Black Swan was talking to Jenna. Melissa believes that Mona was the one who sent her the note.