It's become known that Amanda Waller is set to debut in Arrow Season Two during the sixth episode.
SpoilerTV has the episode title listed as "Keep Your Enemies Closer," stating Amanda Waller will be featured who is an agent of A.R.G.U.S., will be a recurring character, and sends out a team to kidnap John Diggle (David Ramsey).
No cast details are known at this time.
In the DC Comics, Waller does actually head a team known as the Suicide Squad. She is also the liaison between the Justice League and A.R.G.U.S. (more or less equivalent to Marvel's S.H.I.E.L.D.).
A previous episode of Arrow referenced A.R.G.U.S. (Advanced Research Group United Support), titled "Unfinished Business," where the character Lyla Michaels was featured as Harbinger, a high-ranking agent, and an old friend to Diggle.
Arrow returns for Season Two on Wednesday, October 9th at 8pm ET on the CW.