Kryptonsite is reporting that actors have been cast in the roles of Floyd Lawton (Deadshot) and Shayera (Hawkgirl). Deadshot will be played by Bradley Stryker, who had a recent 3-episode stint on Stargate Universe, while the character Shayera/Hawkgirl will be played by Sahar Biniaz.
Biniaz actually appeared in the show previously, playing small roles in three episodes. Both characters will appear in the second episode of season 10. Kryptonsite also reports that Michael Shanks will appear in the episode as well.