Answer: Yi Seong-Gye
Some extra relevant information:
The Joseon Dynasty, one of the longest-ruling dynasties in Korean history, was founded by King Taejo in 1392. King Taejo, also known as Yi Seong-gye, was a prominent military leader who overthrew the previous Goryeo Dynasty and established the Joseon Dynasty. With a strong vision for a centralized and Confucian-based government, King Taejo brought stability and prosperity to the Korean Peninsula. His reign marked the beginning of a new era, characterized by significant cultural, political, and social reforms that shaped Korea for over five centuries. King Taejo’s leadership and establishment of the Joseon Dynasty played a pivotal role in shaping the course of Korean history.