Key: Last Name, First Name - Book first appears in. Short summary.
Thomas, Dean - Book 1. Muggle-born wizard and fellow Gryffindor.
Tom - Book 1. Bartender of the Leaky Cauldron.
Travers - Book 4. Sent to Azkaban for supporting Lord Voldemort.
Trelawney, Professor Sibyll - Book 3. The Divination teacher, who always tries to predict Harry's death.
Trevor - Book 1. Neville's toad who always runs off or gets subjected to Neville's potions.
Troy - Book 4. Chaser for the Irish Quidditch team.