Ron Howard has pitched The Dark Tower adaptation as both a film and TV series starring the same lead actors. Obviously, this has never been done before and is a gamble on the studio's part, as they will have to commit considerable resources into The Dark Tower before they ever know whether the first movie was successful.
Because of this, Ron Howard is really going to need an A-list cast to draw in a new audience. Most horror fans know of The Dark Tower series, but middle america does not, and like many horror films, they are the deciding factor on whether the movie will be a mainstream success.
The NY Post has news that talent agents are rushing to get their clients lead roles for the film. Both Javier Bardem, with Viggo Mortensen have been listed as potential actors for the lead role of Roland Deschain. Of course, like most casting news, this is early and unconfirmed, but I think many fans would be happy to see Viggo Mortensen in that roll. Let's see if he's willing to commit to the three film and TV show deal.