Stranger Things: The First Shadow is a play written by Kate Trefry from an original story by the Duffer Brothers, Jack Thorne, and Trefry. The story serves as a prequel to the events of the television series Stranger Things, exploring the backstory of Henry Creel before he became the antagonist Vecna. The production, directed by Stephen Daldry and Justin Martin, previewed on November 17, 2023, and officially opened on December 14 at the Phoenix Theatre in London's West End. The play began a run on Broadway at the Marquis Theatre, New York City, on April 22, 2025. In an interview with Variety, the Duffer Brothers confirmed the play is canon to the original series, with the series finale referencing events of the play. Both productions of the play in the West End and on Broadway announced their closing dates on June 9, 2026.

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