First off we have the Hawk himself, Katar and I'm casting Sam Worthington in the role because he would be able to pull it off and he looks right to me for Hawkman.
As Hawkgirl (Kendra Saunders) I've cast Alexa Davalos because she can play tough.
My choice for Shadow-Thief (I am pretty sure Katar has fought him) is Kerr Smith.
Michael Landes as Lasso.
A.J. Cook as Hummingbird.
Joseph Fiennes as Fadeaway Man. (thanks anil rickly great choice!)
I'm struggling with casting Lion-Mane.
I will update this if I think of someone or if someone suggests someone who I like for the role. Hawkman is pretty difficult to cast but I'm pleased with how this turned out.