Roger.
Piggy was killed by a boulder. Roger dropped a boulder onto Piggy, and Piggy was stricken by the boulder and fell 40 feet landing on his back.
Piggy is smashed by a boulder at Castle Rock. Roger rolls the boulder down and kills Piggy.
The boulder rolled down the hill with a mighty force, scattering smaller rocks in its path.
He is struck by a boulder that was released by Roger.
Piggy dies in Chapter 11 (Castle Rock), he dies by Roger throwing a giant boulder down the hill where it hits Piggy between his knee and his chin and knocks him unconscious and over the side of the mountain into the sea.
hay
Piggy died when the boys rolled the rock. He fell off the cliff and the rock smashed him into pieces. Poor piggy. Pork, anyone?
They were both crushed under a boulder (page 209)
The boulder which hit Piggy with a glancing blow and knocked him off the cliff was set in motion by Roger. Roger pushed the lever, which was wedged under the rock, and caused it to tumble from the top of castle rock.
Roger kills Piggy with a boulder that sends him flying down 40 feet into a rock which opens his head and then his body gets washed out to sea.
It was Roger who had leaned all of his weight on the lever which made the red boulder go crashing down to where Piggy was which killed him.
Piggy is made fun of throughout the book because he is fat and has "Ass-mar" (asthma). They also use his glasses to start fires and Jack breaks them at one point. No one lets him talk at any of the meetings either. Eventually the kids split into two tribes and they end up stealing and breaking his glasses. Then, Ralph and some other kids go to get them back and the other tribe pushes a large boulder on top of piggy killing him and breaking the conch.