Rob Sawyer is a student in Edward Cullen's 6th period Spanish class.
His only known involvement in the whole series is thinking, "Ugh. Creepy," about Edward. This was said when Rob saw Edward constantly staring at nothing in particular with a massive grin on his face, and then turn to him. In reality, he was eavesdropping Bella Swan by using telepathy to peek through her classmates' thoughts.
It is unknown whether Rob was at graduation or not.