Creatures: Thestral

Thestrals are quite unique in our world and the Wizarding World. They are skeletal, beaked horses with giant wings that can only be seen by those who have seen death, as I said quite unique. They are first heard of when Harry returns in his 5th year at Hogwarts, as they are the ones who pull the "magical" horseless carriage, and since Harry had witnessed Cedric's death the year before he can now see them. He is at first frightened by them, but later in the story he learns how harmless they are and how loyal they can be. They help Dumbledore's Army get to the Ministry, and in turn save the day. Without the Thestrals the Wizarding World wouldn't have that unique charm.