Stephen Amell stars as Oliver Queen, with principal cast members David Ramsey as John Diggle, Rick Gonzalez as Rene Ramirez, Juliana Harkavy as Dinah Drake and Katie Cassidy as Laurel Lance also returning from previous seasons. Katherine McNamara, Ben Lewis, and Joseph David-Jones, who previously recurred as the adult versions of Mia Smoak, William Clayton and Connor Hawke, were all promoted to starring status, as was LaMonica Garrett, who stars across multiple Arrowverse shows as the Monitor. Former series regulars Emily Bett Rickards, Colin Donnell, Susanna Thompson, Paul Blackthorne, Colton Haynes, John Barrowman, Willa Holland, Echo Kellum, Sea Shimooka and Josh Segarra all returned as guests.
