Few of the students in Hagrid’s Care of Magical Creatures class could see the Thestrals during Harry’s fifth year (only Harry, Neville, and an unnamed “stringy” Slytherin boy who may be Theodore Nott). People used to think they were bad omens, that seeing them meant bad luck, but this is just superstition.

Thestrals have an amazing sense of direction and move magically fast through the air. Dumbledore used them to travel if he didn’t care to Apparate.

Harry and a group of students flew Thestrals from Hogwarts to the Ministry of Magic in an attempt to rescue Sirius. Thestrals were also ridden by Kingsley, Hermione, Bill, and Fleur in the Battle of the Seven Potters.

In 2017 when Albus Potter went to Hogwarts for the first time, his brother James tells him to watch out for the Thestrals, thoroughly scaring his brother. Harry reassures him that Thestrals are gentle creatures.

Luna Lovegood is also able to see Thestrals, since she saw her mother die at the age of nine. Everyone who cannot see them assumes that the Hogwarts carriages magically pull themselves.

The Elder Wand contains a Thestral tail hair, a highly unusual wand core.

In 1927 Auror Rudolph Spielman brought a Thestral-drawn black carriage resembling a hearse to MACUSA in New York City to transport prisoner Gellert Grindelwald back to Europe, but he was able to escape, ironically with the Elder Wand – containing a Thestral tail hair.