In Spider-Man 3 , Sandman is revealed to be the killer of Peter Parker 's uncle .
Following the events of Spider-Man 2 , as Peter Parker has managed to finally balance his personal life with his dual life as the masked vigilante : Spider-Man , along with handling a blossoming relationship with Mary Jane Watson , he encounters and is bonded with a mysterious extraterrestrial symbiote , which enhances his super-human abilites and brings out the darker , more repressed side of his personality , while facing off against his former friend : Harry Osborn , who is now a super-human assassin seeking to avenge his father ’ s death and obsessively hunting down an escaped super-powered convict : Flint Marko , who was the true culprit behind the murder of Peter 's father-figure/uncle : Ben Parker .
Spider-Man 3