Thanks to Anon for the following.
Tyreese if you didn't know is one of the more famous characters from the comics who (up until this point) hasn't been brought into the show. In the comics he is Rick's right hand man after Shane dies.
The person who created this thread has been on the Woodbury set and last month revealed another actor who would be on the show ("Martinez" played by Jose Cantillo), and sure enough, that actor appeared in the third episode of this season. So it's safe to say this recent news is fully accurate.