Mark Twain TonightReview By the time Hal Holbrook made his big screen debut in 1966's The Group, a lot of people were curious to see what he really looked like. This is because the now veteran actor had spent more than a dozen years under white hair and latex touring as Mark Twain in a one man show that remains an institution. Always a busy big screen actor in subordinate roles, Holbrook is probably best known as Twain (an Emmy and a Tony all but cemented that status),