Sunkrish Bala will play the character, Dr. Subramanian, who was glimpsed in the extended trailer as the Indian male with the clipboard in his lap. If I were to take a guess, I'd say he was apart of Zack's college group that stumbled onto the Prison.
Sherry Richards will appear as a recurring co-star named Jeanette. At this point I've found nothing else about her character.
I have also learned that Enver Gjokaj will be making an appearance in the 7th episode "Dead Weight". It's very likely he will be playing either Patrick or Mack, and will be aligned with the Governor. Martinez will also appear in this episode.