I guess you can say that every actor is a 'character actor' on some level. But I think some actors have a wider range. I think that's how you get that mantle.
“If the work is poor, the public taste will soon do it justice. And the author, reaping neither glory nor fortune, will learn by hard experience how to correct his mistakes.”
“To remove this obstacle I repeat or refer to such knowledge as has come under my notice, my own previously expressed views, and also describe and exhibit my last experiments and explain their novelty and utility.”