约西亚·威拉德·吉布斯（英语：Josiah Willard Gibbs，1839年2月11日－1903年4月28日）是一位美国科学家。他在物理学、化学以及数学领域都做出了重大的理论贡献。通过引入热力学理论，是物理与化学链接成为结实累累的物理化学的关键促使者之一。同时，他还与詹姆斯·麦克斯韦及路德维希·玻尔兹曼共同创建了统计力学理论，并引入了“统计力学”这个术语。这一理论从统计角度将热力学定律解释为大量微观粒子系综性质的宏观表现。他还将麦克斯韦方程组引入物理光学的研究，并与英国科学家奥利弗·亥维赛各自独立发展了现代矢量分析理论。

Josiah Willard Gibbs (February 11, 1839 – April 28, 1903) was an American scientist who made important theoretical contributions to physics, chemistry, and mathematics. His work on the applications of thermodynamics was instrumental in transforming physical chemistry into a rigorous deductive science. Together with James Clerk Maxwell and Ludwig Boltzmann, he created statistical mechanics (a term that he coined), explaining the laws of thermodynamics as consequences of the statistical properties of ensembles of the possible states of a physical system composed of many particles. Gibbs also worked on the application of Maxwell's equations to problems in physical optics. As a mathematician, he invented modern vector calculus (independently of the British scientist Oliver Heaviside, who carried out similar work during the same period).