hamlet killed polonius by accident. polonius was hiding behind the arrays in gertrudes room and hamlet thought it was claudius so he stabbed him with his sword only to find that it wasnt cladius, but polonius.
Polonius dies in the play. Hamlet kills him while he is in Gertrude's room. Polonius was spying on Hamlet. Hamlet thought that there was a mouse behind the curtain so he swung his sword and killed polonius while he was behind the curtain.
Polonius is the chief counsellor to the King of Denmark and father to Ophelia and Laerates.He is killed by Prince Hamlet who thinks it is Claudius while Polonius was hiding behind curtain to listen to Ophelia & Hamlet .