This book, the only one Anna Sewell ever wrote, is a little bit tough to categorize. It spans a few different categories, and it arguably even has a tinge of fantasy to it since horses obviously can't write books. That said, Black Beauty reads like a true account of one horse's life, and can even technically be considered a coming-of-age tale since the book begins with Beauty's childhood and follows him through adulthood.
Nowadays, this story can also be classified as historical fiction, since it vividly describes aspects of life in Victorian England. However, since it was also written in Victorian England, it wasn't exactly historical when it was published. See what we mean? It's a little tricky to pin this stallion down.