Dolphin Interferon-Gamma (IFN-γ) is a type II interferon produced primarily by activated T lymphocytes and natural killer (NK) cells in dolphins, particularly the bottlenose dolphin (Tursiops truncatus), where it plays a central role in cell-mediated (Th1-type) immunity. IFN-γ signals through the IFN-γ receptor complex (IFNGR1/IFNGR2), activating JAK/STAT1 pathways and inducing genes involved in macrophage activation, enhanced antigen presentation via upregulation of MHC class I and II molecules, and promotion of cytotoxic T-cell responses. In dolphin health, IFN-γ is important for defense against intracellular pathogens and viral infections, including cetacean morbillivirus, herpesvirus, Brucella spp., and other emerging marine pathogens, where balanced Th1 responses contribute to pathogen control while limiting excessive inflammation. Altered IFN-γ expression may reflect immune suppression associated with environmental stressors such as pollutant exposure or harmful algal blooms. In marine mammal and comparative immunology research, characterization of dolphin IFN-γ supports studies of host–pathogen interactions, immune adaptation to marine environments, conservation medicine, and evaluation of immune health in sentinel species, providing insight into cell-mediated immunity relevant to both wildlife health and human infectious disease biology.