<p>Heat pipes are essential thermal management devices widely used in industrial applications, with their efficiency significantly enhanced through the use of advanced working fluids. This review explores the role of nanofluids and hybrid nanofluids in heat pipe systems, emphasizing their superior heat transfer performance compared to the conventional fluids. Nanofluids, stable suspensions of nanoparticles in base liquids, exhibit enhanced thermal conductivity and heat transfer coefficients, leading to improved system reliability. Hybrid nanofluids, containing two or more nanoparticle types, provide synergistic effects that further augment thermal performance beyond single-particle systems. The review analyzes the use of these working fluids across various heat pipe configurations, including cylindrical, flat, looped, gravity-assisted, oscillating (pulsating), and circular types. Each configuration demonstrates distinctive thermal enhancement mechanisms when integrated with nanofluids. External factors such as magnetic fields and vibrational effects are also examined, as they influence nanoparticle behavior and heat transport efficiency. While significant progress has been made with single nanoparticle nanofluids, hybrid nanofluids remain relatively underexplored. Key research gaps include the need of optimized nanoparticle combinations, stability, and scalability. This study identifies these challenges and outlines future directions to advance nanofluid-enhanced heat pipe technology for next-generation thermal management applications.</p>