Oh, David Harbour. Never change. The Stranger Things star is set to make his MCU return as Red Guardian in the upcoming Thunderbolts*. The film’s promotion includes several mysteries most notably, what does the asterisk mean? While Harbour and the cast (which includes Florence Pugh, Sebastian Stan, Lewis Pullman, Wyatt Russell, Hannah John-Kamen, and Julia Louis-Dreyfus), have maintained that mystery, the actor just let slip the worst kept secret in the MCU.