Forster will play Arthur Petrelli, father of Peter (Milo Ventmiglia) and Nathan (Adrian Pasdar) Petrelli, who was said to be dead. It isn't clear when Forster will appear on the show, but it could be within the second hour of the Season 3 premiere on September 22.
Christine Rose, who plays the Petrelli matriarch, Angela, said last month that a big bombshell would be dropped in the premiere. "There's a secret that comes out that if you're a true fan, you're just going to die," she teased. "It's a good Angela secret, and it's [not about] her powers." Whether she's referring to Arthur's return, we don't know.
We'll keep you posted on this interesting development as soon as more information is released. The third season of Heroes will premiere on NBC on September 22.