He told Entertainment Weekly that the Alien star will play an important role in the new story arc involving Chuck's long-lost mother (played by Linda Hamilton).
"Harry will play Harry Dean, the man who comes between Chuck and his search for his Mum," explained Fedak. "Who is he exactly? Well, we'll say this. Only Harry Dean Stanton could play this part."
Fedak also revealed that guest star Dolph Lungdren would play a character named Marco.
The producer teased: "Is he Russian? Yes. Is he a terrifying bad guy? Yes."
Both actors will appear in the season premiere, titled 'Chuck vs. the Anniversary'.
Chuck will return to NBC on September 20.