David J. Tholen is an American astronomer known for his work in planetary science and the study of small bodies in the solar system. He has contributed significantly to the understanding of asteroids and comets, particularly through his research using telescopes and other observational tools. Tholen is also recognized for his involvement in the discovery and characterization of various celestial objects, including the Kuiper Belt and trans-Neptunian objects. His research has helped to enhance our knowledge of the formation and evolution of the solar system.