Dolphin Leukemia Inhibitory Factor (LIF) is a multifunctional cytokine belonging to the IL-6 family—which includes IL-6, IL-11, oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine factor 1 (CLCF1), and IL-27—all of which signal through receptor complexes containing the shared gp130 subunit. In dolphins, particularly the bottlenose dolphin (Tursiops truncatus), LIF binds to the LIF receptor (LIFR) in association with gp130, activating JAK/STAT3, MAPK, and PI3K signaling pathways that regulate cell survival, differentiation, immune modulation, and tissue repair. Dolphin LIF is likely involved in reproductive processes such as embryo implantation and placental development, as well as in hematopoiesis and neural tissue maintenance. In dolphin health, LIF-mediated STAT3 signaling may contribute to regulation of inflammatory responses during respiratory infections, wound healing, and systemic inflammatory conditions, and could influence tissue remodeling in response to environmental stressors such as pollutant exposure or harmful algal blooms. Dysregulated LIF expression may be associated with fibrosis or tumor progression. As dolphins serve as sentinel species for marine ecosystem health, characterization of LIF supports research into immune regulation, reproductive biology, regenerative processes, and comparative IL-6 family signaling. Study of dolphin LIF enhances understanding of cytokine-driven tissue resilience and inflammatory balance in marine mammals and broader mammalian systems.