Harley Quinn

"Do you guys need some counseling? I'm a trained therapist."

- Deranged Squad Female to the Suicide Squad

The deranged Squad female is an unused member of the Suicide Squad, having been deemed too deranged to be trusted on a mission.

Biography
While John Diggle and Lyla Michaels were arguing outside of A.R.G.U.S. holding cells, the woman offered to help them through their problems, claiming she was a trained therapist. Amanda Waller hit her door to shut her up.

Behind the scenes

 * The woman is a reference to Harley Quinn, a long-time enemy of Batman. Along with her quick appearance, she is voiced by Tara Strong, who uses a voice extremely similar to the one she uses for Harley Quinn in the Batman: Arkham games and Injustice: Gods Among Us.
 * If this is indeed Harley Quinn then it indirectly proves the existence of Batman in the Arrow universe, as Harley Quinn would not exist without the Joker and equally the Joker would not exist without Batman.