Purpose: This cross-cultural study examined various domains of dehumanization, including both blatant (viewing autistic people as animal-like, child-like, or machine-like) and subtle (denying agency and experience capabilities) dehumanization, of autistic individuals by Koreans and Americans. Methods: A total of 404 Koreans and 229 Americans participated in an online survey, assessing blatant and subtle dehumanization, knowledge about autism, stigma toward and contact with autistic people, cultural factors, and demographic information. Robust linear mixed-effects regressions were conducted to examine the impact of the target group (autistic vs. non-autistic) and the country (South Korea vs. the US) on dehumanization. Additionally, correlations and multiple regressions were employed to identify individual variables associated with dehumanization. Results: Both Koreans and Americans exhibited more dehumanizing attitudes towards autistic individuals than non-autistic individuals across all domains. Koreans showed greater dehumanization of autistic individuals than Americans in all domains except for the machine-like domain. Stigma toward autistic people was associated with all dehumanization domains among Koreans and with some of the domains among Americans. Individual variables associated with dehumanization varied across countries and domains. Positive contact quality frequently predicted lower dehumanization in both cultures. Conclusions: Non-autistic individuals consistently rated autistic people as less human than non-autistic people. Future research examining how autistic characteristics or societal perceptions that influence the consideration of an autistic person's humanness vary across cultures is needed. Implementing interventions aimed at enhancing non-autistic people's understanding of autistic individuals' agency and experience capabilities and promoting high-quality contact opportunities with autistic individuals may help reduce dehumanizing attitudes.