Harold is a structure used in longform improvisational theatre. Developed by Del Close and brought to fruit through Close's collaboration with Charna Halpern, the Harold has become the signature form of Chicago's iO Theater and the Upright Citizens Brigade Theatre in New York City and Los Angeles. It is now performed by improv troupes and teams across the world.
In 2020 most improv troupes will find a new structure in longform theater and it will no longer be widely used