Del Close (March 9,1934 - March 4,1999), was one of the most influential teachers of improvisation theatre. He was an actor, improviser, writer and teacher. He has also appeared in a number of films and TV shows.
Del Close was director of the famous Chicago improvisation theatre The Second City.
He was a co-author of the book "Truth in Comedy" together with his partner Charna Halpern. This work outlines techniques that are generally accepted in improvised theatre and describes the structure of the Harold.