Rob Dier was the main tritagonist in Friday the 13th: The Final Chapter and the brother of Sandra Dier.
In 1984, Rob Dier left home to avenge his sister Sandra when he heard that she was brutally murdered with her boyfriend Jeff and their fellow counselor's in training at Packanack Lodge, by Jason Voorhees a few days earlier. He traveled to Crystal Lake and camped in the local woods fulling equipped and armed. While traveling to Crystal Lake, he meets Trish Jarvis and her younger brother, Tommy Jarvis, while on the road and helped Trish start her car cause of it stopping by the side of the road. Trish and Tommy bring Rob to their house and he meets Mrs. Jarvis. Later on, he reveals to Trish why he's there at Crystal Lake after they see some dead bodies. Rob tells her and Tommy about Jason Voorhees being responsible for killing his sister. After he tells Tommy to stay in the house, he and Trish go to the house next door to investigate. Shortly after, Trish finds the corpse of Doug nailed to the shower wall, she goes back downstairs and warns Rob that the killer is here. They go up the basement steps but one of the steps break causing Rob to go back downstairs. He's then attacked by Jason Vorhees who pins him against the wall and hacks him to death with a garden hand rake. He tries to fight off Jason so Trish and Tommy can get away and dies in the process, later Rob´s corpse is thrown through a window with a hammer lodged in his head. His corpse along with the corpses of Jason Voorhees, Doug, Ted, Paul, Tina, Terri, Mrs. Jarvis, Sara, Samantha, Jimmy, and the hitchhiker (when the police and paramedics were on the way) were found and taken away to a morgue by police and paramedics.
He was buried next to his sister.
A rather similar character to Rob Dier was used in the remake the only difference being Rob's sister was killed instead of being captured and Rob was also killed by Jason. Clay Miller's sister Whitney Miller was held hostage by Jason it should also be noted that both sisters faced Jason when he was using a burlap sack as a mask.