Del Close is perhaps the least famous of the great comedy maestros of the latter half of the 20th century. The performers he worked with, directed, or taught at the Compass Players in Saint Louis, the Committee in San Francisco, and Second City and the ImprovOlympic in Chicago constitute a who's who—Elaine May, Mike Nichols, Shelly Berman, Fred Willard, Joe Flaherty, John Belushi, John Candy, Bill Murray, Mike Myers, Vince Vaughn, Tina Fey, and Stephen Colbert, to name only a handful. But his ultimate legacy might be theoretical: Close led the movement to reinvent improvisation and establish it as an art form.

Is improv considered an art form now?