Fungi are key components in global biogeochemical cycles, play important roles in manufacturing industries and biomedical research, and influence humans through their impact on global health, agriculture, and biodiversity. Fungi have been isolated from almost every environmental niche across the planet, including from air, soil, fresh water, and the oceans. Although the vast majority of fungi do not exhibit pathogenic traits, some species cause infections in humans ranging from superficial to life-threatening. Moreover, some fungal species are plant pathogens and have devastating impacts on agriculture. In this primer, we aim to provide a broad picture of what makes fungal pathogens unique, as well as the challenges of combating fungal pathogens.