I wanted to cite Harrison Ford but checked the thread to see if anyone else had mentioned him. I mean, he is Harrison Ford and I had a poster of him on my wall as a young 20 something. But he plays every role exactly the same. In every film he is Harrison Ford.
Sean Bean may use the same accent for every role but in no way are his characters the same. YABU in that. Definitely not a one trick pony.
Also just interested. Actors who always speak RP or some generic Southern accent do you think they are one trick ponies?