‘The Walking Dead’s Ross Marquand Didn’t Tell Danai Gurira About Secret ‘Avengers: Infinity War’ Role

The Walking Dead star Ross Marquand boarded the Marvel Cinematic Universe in Avengers: Infinity War — but he had to keep his casting secret from even co-star Danai Gurira.

"I didn't tell anybody," Marquand told EW. "These NDAs on these things are no joke! I literally did not tell anybody until it was out."

Marquand shows up in Infinity War as — spoiler — an apparitional Red Skull, who has been exiled on Vormir for nearly a century and tasked with serving as stonekeeper for the elusive Soul Stone.

"It is tough to keep those secrets," Marquand said.

"Like with The Walking Dead, I think I was silent for seven months before I told anyone about that. With this, it was about six months. And it's tough because you're so excited to tell everyone about these amazing worlds that you're about to become a part of, but you can't tell anybody."

The actor didn't even tell his Walking Dead co-star Danai Gurira, best known for her role as katana-wielding zombie slayer Michonne and now Wakandan general Okoye. The actress made her Marvel debut earlier this year in Black Panther, a role she reprises in Infinity War.

Asked if he at least told Gurira, Marquand said, "No. Because I'm scared to God! These NDAs put the fear of God in you."

Marquand takes over the role from Hugo Weaving, who debuted as the character in 2011's Captain America: The First Avenger, which saw the former Hydra leader seemingly obliterated by the unwieldy power of the Space Stone.

Marquand, who is known to be a skilled impressionist, said it took him a week and a half to nail Weaving's Red Skull voice.

"His performance was incredible, and I really wanted to pay homage to what he did," Marquand said.

"I really feel like he was one of the best comic book villains of all time, so I really hope he's happy with the performance and the film as well."

Avengers: Infinity War is now playing. Gurira and Marquand will return in The Walking Dead season 9, expected to debut this October on AMC.