I actually met Holbrook once, in a manner of speaking. He was doing his Mark Twain Tonight! show in Chicago, and I went to it -- and then afterwards went backstage, spoke briefly and got his autograph on the program.
Holbrook began performing Mark Twain Tonight in 1955. He wrote a wonderful book in the mid-1960s -- aptly titled Mark Twain Tonight!: An Actor's Portrait. It was part-memoir, telling how he developed the show, and part a collection of Twain's works that he used in the show. One story that I remember is that he had performed on television, and afterwards got a call for an acting job from the appearance. When he showed up -- as himself, of course, a young actor in his late-30s -- the producer was aghast. He'd thought he had hired an old man.
Holbrook won a Tony Award in 1966 when he brought his Mark Twain Tonight! to Broadway -- and during the run the performance was recorded for a CBS TV special. (Holbrook brought the show to Broadway three times, the last time in 2005 at age 80.) For such an iconic role, he was able to transcend it and had a long career in TV and film, winning five Emmys and getting one Academy Award nomination for his role in Sean Penn's movie Into the Wild. He also famously played 'Deep Throat' in the Oscar-winning Best Picture, All the President's Men. One of my favorite of his shows was a little-remembered one. It was one of the "wheels" on the series The Bold Ones which alternated shows each week, Holbrook's being called The Senator about an idealistic, somewhat controversial U.S. Senator. Only eight episodes were made over two years, but they were wonderful. One of my good friends, David Rintels (who won several Emmys of his own and the Broadway play Clarence Darrow with Henry Fonda) wrote on The Senator, and he and Holbrook stayed friends.
Here's part of a very interesting reminiscence that Hal Holbrook gave for the Television Academy three years ago when he was 92. He talks about how he unexpectedly developed the Twain show (oddly with somewhat of a roundabout personal connection with Twain himself). It's only about 10 minutes and ends with the creation, before getting into the later development of the show, but it's fascinating -- in large part because he not only tells the story, but in a way acts it out, as he remembers the details. The "Ruby" he mentions at the beginning is his first wife, Ruby Johnston, with whom he was performing at the time, I believe in a two-person show.
And here is seven minutes of Hal Holbrook in easily his most famous role, that 1967 TV special recorded live during a performance of Mark Twain Tonight! on Broadway. Keep in mind as he slowly creaks around on stage that he was 42 at the time.