In 'Hamlet', the character killed while hiding behind a curtain in Gertrude's chamber is Polonius.
Polonius is the elderly chief counsellor to King Claudius and the father of Laertes and Ophelia. He is long-winded, meddlesome, and convinced that he can uncover the reason for Hamlet's apparently strange behaviour. His spying helps make him an emblem of the surveillance surrounding Hamlet at Elsinore.
In Act III, Scene 4, Polonius hides while Hamlet confronts his mother, Gertrude. When Polonius hears Hamlet's intense accusations, he cries out for help. Hamlet assumes the concealed figure is Claudius and thrusts his sword through the hanging fabric, killing Polonius.
The wording varies between productions and editions: Shakespeare's text commonly refers to an “arras” or tapestry, while modern staging often uses a curtain. The victim remains Polonius. His death has major consequences: Claudius sees Hamlet as an immediate threat, Laertes returns seeking revenge, and Ophelia's grief and madness intensify. Horatio, Gertrude, and Claudius are all alive after this specific scene.