The Soviet prison guard who helps Hopper escape in Stranger Things season 4 is Dmitri Antonov.
Dmitri works at the Kamchatka prison camp where Jim Hopper is held. He initially agrees to help Hopper secure his freedom after Hopper offers him money, but the plan is disrupted when the prison authorities discover the escape attempt. Dmitri is imprisoned alongside Hopper and later becomes an ally in the larger effort to get out of Russia.
Dmitri is also known by the codename “Enzo,” taken from the Italian restaurant where Hopper and Joyce Byers had planned to meet. Joyce receives messages from the guard under that name, so viewers may remember Enzo rather than Dmitri. “Enzo” is an alias, while Dmitri Antonov is the character’s actual name.
His storyline connects the Russian prison plot to Joyce and Murray’s rescue mission. After surviving the prison’s brutal Demogorgon spectacle, Dmitri works with Hopper, Joyce, and Murray to escape the Soviet facility and leave Russia.