Joss Whedon has revealed Cobie Smulders' hectic schedule could limit her appearances in his SHIELD TV series.
The How I Met Your Mother star revealed last month that she was in talks to make a cameo appearance as her Avengers Assemble character Agent Maria Hill in the pilot of the Marvel spin-off, which Joss is working on for American network ABC.
But the writer and director told TV Line that Cobie's schedule "will permit very little" involvement, adding "if we can get a hold of her anytime, we will".
Joss said viewers should expect "not a ton" of familiar faces in the pilot, but admitted there were cameos planned for the future. He added: "Right now, I want to involve people in the characters that we've created for the show."
The Buffy The Vampire Slayer creator has co-written the series and will direct and executive produce.
He revealed: "I'm excited about the show because it's a very hopeful show. It's not about murder, and it's not about crime, and it's not people looking into their own belly buttons. It's about people who are trying to help each other, and that's one of the things I loved about comic books. They had costumes and the villains were cool [but] they stood for something, and I like doing a show that does that."
He added: "We're trying very hard to be true to [Marvel's] ethos and also to the structure of their universe. So it is definitely a Marvel show."