This thesis investigates the audiovisual translation of fictional languages in multilingual film franchises using Spanish dubbing of the invented Klingon language in Star Trek: The Next Generation as a case study. This invented language appears throughout the series, often to increase the realism of the science fictional universe or reveal cultural information about Klingons. Building on Corrius and Zabalbeascoa’s (2011) descriptive framework used to analyze audiovisual translation of multilingual film, this thesis examines the use of Klingon words and phrases and their associated meanings in the original English series and how they are represented in the Spanish dubbed version as well as the possible interplay between the dubbed renditions and the nature of Klingon as an invented language. Given that most audience members cannot be assumed to know Klingon, the meaning of Klingon words and phrases must be communicated either through context clues, such as dialogue explaining the term, or through other on-screen devices, such as subtitles. When dubbed into other languages, the presence of Klingon language in Star Trek: The Next Generation poses unique challenges for audiovisual translators. Compared to a solely text-based translation, effective dubbing must consider audiovisual constraints (e.g., space restrictions, image synchronization) and the presence of non-verbal audiovisual cues to convey meaning. In the case of Star Trek, the Klingon language complicates the task of dubbing the series from English into Spanish in light of the various functions that Klingon plays in the original series and the associated linguistic and cultural aspects of its use. The thesis concludes with a discussion of how the multimodal nature of audiovisual translation requires greater reflection on the contextual and paralinguistic elements present in multilingual film series to better account for productions involving invented languages.