From NBC's official press release:

Sylar goes back to his roots – John Glover guest stars as Sylar's biological father.

When Sylar (Zachary Quinto) comes face-to-face with his long lost father (guest star John Glover), the reunion proves to be what he least expected.  Elsewhere, after receiving a tip from "Rebel," Claire (Hayden Panettiere) must decide if she will help her sworn enemy, Eric Doyle (guest star David Lawrence XVII), evade capture.  Meanwhile, as "The Hunter" (guest star Zeljko Ivanek) plans to uncover the Petrelli family's secrets and take control of Nathan's (Adrian Pasdar) operation, Matt (Greg Grunberg) finds himself in the spotlight and on the verge of leveling Capitol Hill.

Heroes also stars Jack Coleman, Ali Larter, James Kyson Lee, Masi Oka and Cristine Rose also star.


Source: NBC
(Image courtesy of NBC)