The order Chaetothyriales is a group of fungi within the class Eurotiomycetes, primarily known for their diverse ecological roles and melanized (darkly pigmented) cell walls. Many species are extremotolerant, thriving in harsh environments such as polluted soils, rock surfaces, or high-radiation areas. Members of Chaetothyriales include both saprophytes, which decompose organic matter, and opportunistic pathogens, capable of infecting humans and animals, particularly causing cutaneous, subcutaneous, or systemic infections. They often form slow-growing, dark, septate hyphae and produce asexual spores, with some genera also exhibiting sexual stages. Their unique tolerance to environmental stress and potential for human infection make them of interest in both medical mycology and environmental microbiology.