Dourif is top quality actor. There is no doubt. And yeah, he's very underrated. I felt more sorry for Dourif having his part cut out of the theatrical release of ROTK than I did for Christopher Lee.
Did you know that he spoke in the deep English accent of Grima the ENTIRE time he was in New Zealand shooting. On his last day he automatically reverted to his American accent and everyone thought he was hamming his actual accent up! He's a method actor extraordinaire!
I think Dourif's Grima was one of the best acted roles in the entire trilogy and that's up against some tough competition.
As I said in another thread a few days ago. Killing Lon Suder off in Voyager at the end of Season 2 was one of the biggest mistakes the writers ever made. And again, that's up against some tough competition. Dourif should of been a main character. Suder rocked.