User blog comment:Sonamy4ever2912/Voice Cast for the Deadly Six/@comment-4802891-20131007041327

As far as VA are concerned I don't know.

For seiyuu however, Nakata Jôji is voicing Zavok (Gamma in Sonic Adventure, Howdy Jones in One Piece, Alucard in Hellsing, Kotomine Kirei in Fate/Stay Night... and a LOT more) and if you know his voice, you can tell by ears alone.