Ovine Interleukin-6 (IL-6) is a multifunctional pro-inflammatory cytokine and a central member of the IL-6 cytokine family—including IL-6, IL-11, IL-27, IL-31, leukemia inhibitory factor (LIF), oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), and cardiotrophin-like cytokine factor 1 (CLCF1)—which signal through receptor complexes containing the shared gp130 subunit to activate JAK/STAT and MAPK pathways. In sheep (Ovis aries), IL-6 plays a critical role in regulating acute-phase protein production (such as haptoglobin and serum amyloid A), leukocyte recruitment, B- and T-cell differentiation, fever induction, and systemic inflammatory responses during infection, tissue injury, and metabolic stress. Elevated IL-6 expression is associated with economically significant ovine diseases including mastitis, pneumonia, foot rot, caseous lymphadenitis, parasitic infestations, and viral infections such as ovine progressive pneumonia (maedi-visna), where it contributes to inflammation and disease severity. IL-6 also plays an important role in reproductive physiology and periparturient immune modulation. As a biomarker of immune activation, ovine IL-6 is valuable for herd health monitoring, vaccine evaluation, and assessment of inflammatory status. In veterinary and translational research, characterization of ovine IL-6 and related family members supports studies of host-pathogen interactions, small ruminant immunology, reproductive immunology, and development of immune-based strategies to improve animal health, productivity, and welfare.