There will be a new character in The Walking Dead television show, named Milton (played by Dallas Roberts), who will be a part of the Woodbury group. It sounds like he’ll be somewhat of a scientist or just curious about the walkers.

“Milton is the details guy,” explains exec producer Robert Kirkman. “He’s the guy that works with the Governor, who is monitoring all situations and is trying to help the Governor make sense of this world that they’re living in. He’s not exactly a scientist, but he’s a smart guy that is trying to find out how zombies behave. Watching him do his little experiments is going to be a lot of fun.”
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“We were examining, ‘How do people survive in this apocalyptic world, and what can people contribute?’” says Mazzara. “And we didn’t think it was plausible that every single character we meet is an efficient zombie killer. We just didn’t buy that everyone we know would be active and deft enough to kill every walker. We wanted to show how other people survive, and Dallas has come in and helped us establish that character. He just adds a lot of heart and humanity to Woodbury, which further complicates what that is. That is a real town with real people and real survivors. It’s not necessarily a group of bad guys.”
Source: insidetv.ew.com

The first half of season 3 is already done so since we just heard about Milton, I think it’s safe to assume we won’t see him until the second half of season 3. Just so others know, Milton was not a character in the comic books.