The master’s thesis titled "Costume Design for J. R. R. Tolkien's Silmarillion" elaborates the theme and methodology of the work in the introductory part. The second part is divided into three main thematic units. The first part is theoretical and includes an overview of the life and literary work of J.R.R. Tolkien within the framework of the fantasy genre in the popular literature of the 20th century, then follows the interpretation of his book The Silmarillion, and the contextualization of that work with the screen adaptations of two other Tolkien works - The Lord of the Rings and The Hobbit based on whose costumes is what inspired this work. In this part, the influence of medieval and Venetian renaissance styles of clothing was also researched, which served as inspiration for both the writer when describing his characters and the costume designers for the screen adaptation of his two books mentioned. The second part of the work is experimental and includes the methodology of making a costume inspired by the sea god Ulmo, as well as analysis and sketches of the realized costume. The last unit is a practical part in which the cut is worked out and the costume/dress is realized, as well as pictures of the finished item.