Carly Fiorina - played by herself. After all, she seems to be an actress now, "playing" the role of a technology CEO. (i.e. she's got the "style" right but there's no substance underneath; she's always trying to give a "performance" rather than results).
Walter Hewlett - played by Michael Douglas. Not that I think there's a lot of resemblance, but I'd love to see Walter take on Carly and the BoD the way Michael Douglas (as Gordon Gekko) took on the do-nothing corporate "insiders" in the movie "Wall Street". And frankly, Walter (along with help from David W. Packard, etc.) seems to be doing just that! Go get 'em Walter!