Key: Last Name, First Name - Book first appears in. Short summary.
Nagini - Book 4. Lord Voldemort's trusty snake.
Norbert the Norwegian Ridgeback - Book 1. Hagrid's pet dragon that he raised, but had to let him go when he got too big and fercious.
Norris, Mrs. - Book 1. Filch's pet cat that informs him on students doing naughty things.
Nott - Book 4. A Death Eater.