At the end of Season 3, audiences saw the Soviet’s lab blown up; therefore, closing the gate to the Upside Down, at least the one located in Hawkins, Indiana. 

Unfortunately, Hopper was locked inside when Joyce (Winona Ryder) turned the key, and fans questioned if the Hawkins Police Chief survived the explosion. A post-credit clip saw an experimental Russian base, and Soviet soldiers mentioning “the American.” However, it was not confirmed at the time if it was Hopper. 

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