Sangeetha Pulapaka

Thestrals are invisible except to those who have seen death; Harry can see them, but because his friends can't, he is initially afraid that they are a sign that he is going mad. It is Thestrals that pull the (apparently horseless) Hogwarts carriages to and from the train station at the beginning and end of the school year. They are carnivorous, and are attracted to the scent of blood. They are strong flyers and can carry you anywhere you want to go, and they have a good sense of direction. Because of the relationship with death, it is widely believed that seeing a Thestral is a bad omen.

It is not until Hagrid teaches a class on Thestrals that Harry is reassured that these are real creatures and he is not losing his mind. Only three students in Harry's Care of Magical Creatures class can see the thestrals: Harry himself, Neville Longbottom and a "tall, stringy Slytherin" who the author has identified as Theodore Nott, Luna Lovegood (who saw her mother die) can see them as well; but she is in Ravenclaw, and a different year, so she attends a different class. Hagrid is proud of having the largest domesticated herd of Thestrals in the UK.

The ability of Thestrals to fly, and their navigation ability, will prove invaluable to Harry when he, RonHermione, Neville, Ginny, and Luna need to get to the Ministry of Magic. We will see them again briefly in Harry Potter and the Deathly Hallows