Key characters killed on 'Walking Dead'

Rick Grimes, played by Andrew Lincoln, center, tries to keep some sense of normalcy in a post-apocalyptic world overrun with walkers on AMC's "The Walking Dead," but characters come and go quickly on the gruesome show. Here's a look at some of the key characters we've lost:

Rick Grimes, played by Andrew Lincoln, center, tries to keep some sense of normalcy in a post-apocalyptic world overrun with walkers on AMC's "The Walking Dead," but characters come and go quickly on the gruesome show. Here's a look at some of the key characters we've lost: