Without question one of the show's worst characters, Doran Martell did nothing but sit in his chair and stare into space whenever he appeared. As hateful as Ellaria Sand (more on her soon) was, it was easy to understand her frustration with this inactive, useless ruler.
Doran was a poorly-written character and Alexander Siddig wasn't quite able to lift him out of the gutter despite his evident talents. It was essentially a one-note, one-tone-of-voice performance during which he seemed to be on the verge of nodding off most of the time.
In all honesty this was more the fault of the writing rather than Siddig, but nevertheless, it's one of Game of Thrones' worst performances.
Film Studies graduate, aspiring screenwriter and all-around nerd who, despite being a pretentious cinephile who loves art-house movies, also loves modern blockbusters and would rather watch superhero movies than classic Hollywood films. Once met Tommy Wiseau.