J. August Richards played Charles Gunn for Whedon on the Angel series for five years.
TVLine reported the news of Richards' involvement in S.H.I.E.L.D. but little else is known about the role as it's being described as "super secret."
J. August Richards joins Marvel Studios veteran Clark Gregg, who returns as Agent Coulson, along with Brett Dalton as Agent Grant Ward, Iain De Caestecker as Agent Leo Fitz, Elizabeth Henstridge as Agent Gemma Simmons, Ming-Na Wen as Agent Melinda May, and Chloe Bennet as Skye.
Joss Whedon directed and co-wrote the pilot, with S.H.I.E.L.D. looking to air this Fall on ABC.
J. August Richards recently starred in episodes of Warehouse 13, The Mentalist and Emily Owens M.D.