Reports of marine parasites and diseases are increasing worldwide; however, they are woefully understudied compared to their terrestrial counterparts. Part of the disparity stems from the logistical difficulties of working and sampling in the ocean, as well as the open nature of many marine populations, which decreases the visibility and tractability of marine parasites. As we work to build the knowledge base of marine parasites and diseases, we must recognize that such a process is more than just cataloguing species. Rather, we need appropriate frameworks for understanding which parasites and diseases are impactful, how they affect species other than their hosts, how they are exacerbated by environmental factors, and how they may adapt to conditions of global change. The Ecology and Evolution of Marine Parasites and Disease explores how parasites and diseases affect marine life, ecosystems, and global change. As reports of marine disease rise, this timely volume offers a rare and accessible look at how scientists detect, study, and understand these often-overlooked threats. Written by leading experts, the book brings together real-world case studies, large-scale research, and cutting-edge evolutionary insights. It provides readers with a vital framework for understanding how marine disease spreads, evolves, and impacts life beyond just the host. This is an essential resource for marine science, conservation, and environmental change.