Stith Thompson (March 7, 1885 – January 13, 1976) was an American scholar of folklore. He is the "Thompson" of the Aarne-Thompson classification system, which indexes certain folktales by their structure and assigns them AT numbers. He also developed an alpha-decimal motif-index system (A~Z followed by numeral) for cataloging individual motifs.
Useful in the vast scope of its information; Stith works to be inclusive of a large number of cultures, focusing the first half of the book on Indo-European folklore, and the second half on the folklore of "primitive" cultures (e.g., Native American). This text is a reflection of the 1940s school of folklore studies, which makes it pretty dated. It's purpose is to function as a laundry list of folklore tropes in different parts of the world, naming and categorizing each one for the benefit of a Western audience, and it serves that purpose quite well. It does not, however, seek to explore the cultural context of the tropes and what they mean to the cultures that use them. If you have a casual, nonacademic interest in general folklore, this book will probably fulfill your needs.