Autism has become a familiar theme in television and cinema over recent years. Nevertheless, autism’s depiction in television documentary formats is little discussed in scholarly literature and is often taken for granted due to assumptions about objectivity, truth and narratological authority associated with the documentary form. This thesis examines the evolving portrayal of autism in British television documentaries between 2002 and 2020. During this period, broadcasters, it is argued, have increasingly replaced homogenous, deficit-laden depictions with more heterogeneous portrayals that present neurodiverse perspectives. The dissertation finds that autism representation in British documentaries is shaped by the interplay among various autism conceptualisations, historical stereotypes, narrative conventions and recent developments in digital media technology. Science-inflected documentary genres have tended to present autism according to the medical model of disability, which relies on problematic stereotyping. Entertainment-focused documentaries, meanwhile, idealise and normalise autism through hybridised and sometimes sensationalising formats, curative narratives and the construction of autistic celebrity personas. And lastly, first-person oriented documentaries in have elaborated more neurodiverse portrayals of the condition in relation to more progressive disability models, but could further diversify autism representation by including voices from a broader range of perspectives from across the autistic spectrum, such as those of autistic people with a learning disability or those with communication difficulties.