Eleven calls Dr. Martin Brenner “Papa” in “Stranger Things.” The name reflects the artificial parental role Brenner created for himself while directing the experiments at Hawkins National Laboratory.
Brenner oversees a secret program involving children with unusual psychic abilities, including Eleven, whose birth name is Jane Ives. He presents himself as a caring father figure, but his treatment of the children is controlling and abusive. He separates Eleven from her mother, subjects her to repeated experiments, and uses affection and fear to maintain authority over her.
The title “Papa” is used by Eleven and other laboratory children, making it more than a private nickname. It is part of Brenner’s manipulation: he encourages the children to see him as a protector even while exploiting their powers. Matthew Modine plays Brenner, whose apparent death in season one is later revealed to have been only temporary.
“Papa” should not be confused with “Daddy,” “Father,” or “Doc.” Those options capture a general parental or medical relationship, but the show’s established canonical name for Brenner is specifically “Papa.”