I once saw Hal Holbrooke in a Broadway theater. But not on stage. He was seated a few seats away from me for a performance in 1986 of Arsenic & Old Lace at the 46th St. Theater in New York. That production starred William Hickey, Polly Holiday, Jean Stapleton and Tony Roberts.
The next time I saw Holbrooke was on stage in San Francisco, doing his Mark Twain show.
https://www.nytimes.com/2021/02/02/theater/hal-holbrook-dead.html
RIP