Soldato
Attenborough, Freeman and Piggott-Smith (his work on military things such as Battlefield is great). Also, Laurence Olivier's narration of "The Wiorld at War" is stunning.
Ian Mckellen
Quite suprised it took almost 20 posts til someone mentioned him [Ian McKellen].
I quite like Chris Barrie and Robert Lewellyn - but I'm a Red Dwarf fan so a bit bias.