Teodoro Andal Agoncillo (November 9, 1912 – January 14, 1985) was a prominent 20th-century Filipino historian. He and his contemporary Renato Constantino were among the first Filipino historians renowned for promoting a distinctly nationalist point of view of Filipino history (nationalist historiography). He was also an essayist and a poet. Agoncillo is related to Don Felipe Agoncillo, the Filipino diplomat who represented the Philippines in the negotiations that led to the Treaty of Paris (1898), and Doña Marcela Agoncillo, one of the principal seamstress of the Philippine flag.