I know most of them, although I had to look some of them up. Some of the characters are relatively new and minor (like Sasha), so we don't know much about them.
I had to laugh when I saw this Onion headline:
'Walking Dead' Writers Regret Naming Every Single Character 'Rick'
I was watching a few weeks back when Rick was AWOL and everyone was saying, "Where's Rick?", "Have you seen Rick?", "Rick will handle all this," or "We'll settle it when Rick gets back."
And I'm thinking, "Okay, ... which one is Rick again?"