A person who rides a skateboard, which is a plank of wood with wheels. Skateboarders come in all sizes and shapes.
A skateboarder also likes to bitch about rollerbladers and bmx'ers are in the way, when their certainly wasting more space than any of the two earlier mentioned.
skateboarder: Dude, FUCK OFF! You're blocking my way the the quarter pipe!
rollerblader: Well, it was actually my turn to ride.
skateboarder: go away *picks up board and throws at rollerblader*