Frank Herbert’s Dune (1965) and Denis Villeneuve’s cinematic adaptation, comprising Dune (2021) and Dune: Part Two (2024), construct Arrakis as an ecological system in which human existence is inseparable from environmental conditions. While much of the critical discussion surrounding Dune has focused on ecology, imperialism, resource extraction, religion, and environmental politics, this article examines the relationship between ecological transformation, posthuman subjectivity, and vulnerability. Thinking of Rosi Braidotti’s conception of the posthuman subject, N. Katherine Hayles’s critique of autonomous humanism, Stacy Alaimo’s concept of trans-corporeality, and Cary Wolfe’s critique of human exceptionalism, the article argues that Dune destabilises the autonomous human subject by presenting identity as relational, embodied, environmentally embedded, and vulnerable. Water scarcity, suits, spice, sandworms, Fremen ecological knowledge, and Paul Atreides’s transformation collectively demonstrate that the human subject cannot exist independently of material and nonhuman systems. The films extend this argument through visual, auditory, and corporeal representations of the desert, making ecological vulnerability perceptible through cinematic form. Villeneuve’s adaptation particularly emphasises the physical scale of Arrakis, the vulnerability of the human body, the transformative effects of spice, and the ambiguous relationship between Paul and the Fremen world. The article contends that vulnerability in Dune should not be understood merely as weakness but as a constitutive condition of posthuman existence. By transforming scarcity into ecological knowledge and interdependence, Herbert and Villeneuve challenge human exceptionalism and propose a form of subjectivity in which survival depends on recognising the interconnectedness of human, technological, ecological, and nonhuman systems.