On July 20th, 1973, Bruce Lee died of a cerebral edema (which is a sweeling of the brain) in Hong Kong. Bruce Lee was in the middle of filming his next movie called Game of Death. One of Lee's most popular films Enter the Dragon was three weeks away from the release date. The autopsy showed that Bruce Lee had suffered a very strong reaction to a painkiller called Equagesic which he had ingested after complaining of a headache.
The reaction was said to be caused by meprobamate which is a muscle relaxant found in the medication. There are a lot of conspiracy theories about his death. One such rumor is that he, his brother and his son were killed because of a curse that was put on the family.