Ovine 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—and signals through receptor complexes containing the shared gp130 subunit. In sheep (Ovis aries), 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. Ovine LIF plays a critical role in reproductive biology, particularly in uterine receptivity, conceptus elongation, and embryo implantation, making it highly relevant to fertility management and assisted reproductive technologies in sheep production systems. LIF is also involved in hematopoiesis, neural cell maintenance, and modulation of inflammatory responses during infections such as mastitis and respiratory disease, where STAT3-mediated signaling influences tissue remodeling and immune balance. Dysregulated LIF expression may contribute to fibrosis or tumor progression in certain contexts. As both a reproductive and immunomodulatory cytokine, ovine LIF is important in studies of embryo culture systems, stem cell biology, inflammatory regulation, and cytokine network dynamics. Characterization of ovine LIF supports veterinary research aimed at improving reproductive efficiency, understanding inflammatory and fibrotic disease mechanisms, and advancing regenerative and translational applications in small ruminant health.