Dr. Caleb Subramanian, portrayed by Sunkrish Bala, is a character in the television series The Walking Dead.
Dr. Subramanian is a newcomer to the prison community. Not much is known about him, besides the fact that he is a physician, and he and Hershel Greene seem to be friends. After the breach on Cell Block D dies down, Dr. Subramanian assesses what may have caused the outbreak and what steps the group should take to prevent another such disaster.
"Dr. S" later comes down with the flu and tells Sasha Williams they have to warn the healthy members of the prison community that the virus is spreading. His condition seriously and quickly deteriorates, although he reveals that he has brought several guns in case of another outbreak.
He later succumbs to the sickness after Hershel gives him a checkup. Dr. S later reanimates, and Hershel remorsefully puts him down through Dr. S' locked cell door, after snapping the walker's arm. Hershel later returns to Dr. S' cell and mourns his friend.