ignavus suggested, below, that it was probably more of a personality match than a physical match. And if I think about it, I agree; he probably gave a great reading. But when I think "Karl Urban" I picture The Reaper, Lord Vaako, Éomer Éadig. Maybe the promos will convince me.

...Which character from Heroes does the Spock guy play? I haven't watched since the first few episodes, so I don't recognize actor names.