The last few years have been something of a Renaissance for genre TV. There's geek culture comedy The Big Bang Theory on CBS, apocalyptic horror series The Walking Dead on AMC, and, of course, HBO's Game of Thrones, which has done more to bring fantasy than any book/show/film since Lord of The Rings. With what's got to be close to the the largest ensemble cast on TV, it makes sense that the show would have had the occasional bit of casting fall through, the occasional slip-up. As such, the following list should provide an interesting look at what might have been had Game of Thrones gone a slightly different route.
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10. Dominic West
Case and point: McNulty himself. The British actor best known as the dogged, alcoholic cop on The Wire was apparently first choice for the role of Mance Rayder, leader of the Wildling forces and self-styled King Beyond the Wall, for Season Three. West apparently turned the role down due to family commitments - shooting would have required relocating to Iceland - though it's hard to believe that three-episode bit part would have kept him away from home for too long. Even so, Ciaran Hinds was able to step in, bringing with him a crustier, less civil version of the authority he displayed as Caesar in HBO's Rome. Given the important role that Mance presumably has left to play in the affairs of Westeros, it's intriguing to consider what a younger, slightly more virile take on the character might have been like.