The thesis explores the theme of hybridity in Octavia Butler's Xenogenesis trilogy and in her last novel, Fledgling, which both deal with complex relationships between humans and a different species. The main focus is on the characters of mixed origin - offspring of two distinct species and beings whose existence is a result of genetic experiments. These individuals occupy a metaphorical "in-between" space where cultural, racial, sexual and other boundaries meet and blur. The theoretical framework follows two sets of ideas - Homi Bhabha's notion of hybridity and the so-called Third Space, and Donna Haraway's cyborg figure. The second chapter of the thesis is centered on the origins and development of the concept of hybridity and its current use in postcolonial discourse. Furthermore, it introduces the most relevant ideas from Bhabha's The Location of Culture and Haraway's "A Cyborg Manifesto" and compares them. The following two chapters are mainly devoted to Butler's hybrid characters, Akin and Jodahs from Xenogenesis and Shori, the protagonist of Fledgling. This section analyses, among other issues, their physical features and special skills connected with hybridity, the construction of their identity, their relationship with others and their relation to the clash between different species and...