Lost star Zuleikha Robinson will join the terrorism thriller as journalist Roya Hammad, while English actor Rupert Friend will play new CIA agent Peter Quinn.
"[Quinn is] an ally of Estes (David Harewood) and will be introduced into Carrie and Saul's life," Gansa told Entertainment Weekly.
"It's not a potential love interest for Carrie (Claire Danes). He's more of an antagonist, actually."
Of Robinson's character, who is secretly working for terrorist Abu Nazir (Navid Negahban), Gansa said: "She's a master manipulator whose cover as a reporter allows her access to people."
Gansa's Homeland co-creator Howard Gordon also promised that none of the show's characters are safe from danger in season two.
"What I Iearned from [my former show] 24 is to exit a character when their story has been told," said Gordon. "That was a show where there were real stakes - characters that you loved could either be arrested or killed. Everybody was fair game."
Homeland will return to Showtime in the US on September 30. Season two is expected to debut in the UK in October.
Photo gallery - Homeland season two: