Ovine Interferon-γ (IFN-γ) is a type II interferon cytokine that plays a central role in cell-mediated immunity and regulation of antimicrobial and inflammatory responses in sheep (Ovis aries). IFN-γ is produced primarily by activated T helper 1 (Th1) cells, cytotoxic T lymphocytes, and natural killer (NK) cells following stimulation by intracellular pathogens or immune signaling molecules such as IL-12 and IL-18. Ovine IFN-γ binds to the interferon-γ receptor (IFNGR1/IFNGR2) expressed on many immune and non-immune cells, activating intracellular signaling through the JAK–STAT pathway, particularly STAT1, which induces the expression of numerous interferon-stimulated genes involved in antigen presentation, macrophage activation, and antimicrobial defense. In sheep, IFN-γ is critical for activation of macrophages, enhancement of MHC class I and II expression, and control of intracellular pathogens including viruses, bacteria, and parasites. Ovine IFN-γ is widely studied in veterinary immunology and livestock disease research; for example, IFN-γ responses are commonly measured in studies of Mycobacterium avium subsp. paratuberculosis infection (Johne’s disease), where IFN-γ production by antigen-stimulated lymphocytes is used as an indicator of cell-mediated immune responses and early infection in sheep.