Much of the following information is gathered from various articles, interviews and message forums. As such it can be considered RUMOR and subject to change or otherwise inaccurate. The webmaster's comments are found in the italicized brackets.
Episode 21: Into Asylum; 3/30/09 2/8/09: Guest character: TECH: 28 - 32. MALE OR FEMALE. PLEASE SUBMIT ALL ETHNICITIES. This brilliant tech is responsible for monitoring classified information...CO-STAR. From Casting Call 1/15/09: Added Episode Title. From HeroSite.net
Episode 22: Turn and Face the Stranger; 4/6/09 2/14/09: Updated the Episode Title from 'Face the Stranger'. From ODI 2/14/09: Added Episode Title. From SpoilerTV 2/14/09: Guest characters: ALENA MIHAILOV: LATE 20s. RUSSIAN. SPEAKS WITH A RUSSIAN ACCENT. MUST BE ABLE TO SPEAK SOME RUSSIAN. A pretty former paid escort, Alena is now being taken care of by a former client with whom she has fallen in love...GUEST STAR; JAPANESE DRIVER: 30 - 45. JAPANESE. A funny, amiable guy from Texas, this truck driver's voice is 100% pure Texan twang...CO-STAR / POSSIBLE 1 DAY GUEST STAR; AGENT DONNER: 38 - 45. MALE. PLEASE SUBMIT ALL ETHNICITIES. MUST BE IN GREAT PHYSICAL SHAPE. Agent Donner is an FBI agent heading up an important mission in a top-secret operation...LARGE CO-STAR / POSSIBLE 1 DAY GUEST STAR; AGENT 1 & 2: 28 - 45. PLEASE SUBMIT MEN AND WOMEN OF ALL ETHNICITIES. MUST BE IN GREAT PHYSICAL SHAPE. EXPERIENCE HANDLING WEAPONS A PLUS. These men/women are FBI agents taking part in a top-secret military operation...CO-STAR / POSSIBLE RECUR. From Casting Calls
Episode 24: I Am Sylar; 4/20/09 2/22/09: Added Episode Title. From ODI
Episode 25: ; 4/27/09 2/25/09: Guest characters: LIAM SAMUELS: LATE 30's. CAUCASIAN. Highly educated and extremely charismatic, Liam Samuels is Chief of Staff to the President. Think Rahm Emanuel. GUEST STAR; AIDE: LATE 20's. FEMALE. AFRICAN-AMERICAN. Highly educated staffer to the junior senator from New York. LARGE CO-STAR; SECRET SERVICE AGENT: 30 - 45. PLEASE SUBMIT MEN OF ALL ETHNICITIES. MUST BE IN GREAT PHYSICAL SHAPE. EXPERIENCE HANDLING WEAPONS A PLUS. Secret Service Agent to the President. CO-STAR; SECURITY GUARD: 30 - 45. PLEASE SUBMIT MEN OF ALL ETHNICITIES. MUST BE IN GREAT PHYSICAL SHAPE. EXPERIENCE HANDLING WEAPONS A PLUS. A Security Guard working a high profile event. CO-STAR. From Casting Calls[Someone gets close to the President. We're guessing it's some of the Heroes and he pulls the plug on Nathan and the Hunter, perhaps after one of them saves his life.] 11/15/08: The "Good vs. Evil" storyline gets resolved "at the end of volume four." From Greg Grunberg Interview 10/12/08: This is the finale of Volume 4: "Fugitives." From Behind the Eclipse Week 1 CBR Article