Media depictions of autism have the potential to have either positive or detrimental impacts on the lives of autistic people. This systematic review aimed to examine (1) the accuracy and authenticity of fictional media portrayals of autism (Part A) and (2) the impact of viewing such portrayals on knowledge about autism and attitudes towards autistic people (Part B). Seventeen articles met the inclusion criteria and were included in the review: 14 for Part A and 3 for Part B, comprising five experimental studies. The media reviewed in Part A covered a 30-year period (1988-2017). Several stereotypical and unhelpful portrayals surfaced. Positive portrayals of autism highlighted strengths and reflected nuance. Overall, participants in the fiction conditions in Part B were significantly more likely to attribute positive traits to an autistic person than those in the control conditions, with medium effect sizes ranging from 0.57 to 0.73. There were no improvements in knowledge. Given the small number of studies included in this review, further evidence is needed to understand the conditions under which fictional media may be effective. There is also a need to develop measures that accurately and respectfully measure autistic people's experiences of community knowledge and attitudes.