There has been quite a bit of chatter as to what characters will be introduced in season two of AMC’s THE WALKING DEAD.

THE WALKING DEAD tells the story of the months and years that follow after a zombie apocalypse. It follows a group of survivors, led by police officer Rick Grimes, who travel in search of a safe and secure home. The comic goes on to explore the challenges of life in a world overrun by zombies who take a toll on the survivors, and sometimes the interpersonal conflicts present a greater danger to their continuing survival than the zombies that roam the country. Over time, the characters are changed by the constant exposure to death and some grow willing to do anything to survive.
Robert Kirkman, creator of the comic the series is based on, has talked about it to a number of media outlets and couple of characters seem certain to show up:

Michonne seems a lock. She is a rather mysterious lady that wields a kantana and clearly knows how to use it. Tracie Thoms (DEATH PROOF, CBS series COLD CASE) seems to be the choice of most online.

Maggie Greene also appears set. Maggie becomes romantically involved with Glenn (Steven Yeun). She is the daughter of Hershel Greene, a farmer that allows the survivors to stay on his land for a while.
THE WALKING DEAD was picked up for a second season, which will be thirteen episodes long.