Seungsahn Haengwon, born Duk-In Lee, was a Korean Seon master of the Jogye Order and founder of the international Kwan Um School of Zen. He was the seventy-eighth Patriarch in his lineage. As one of the early Korean Zen masters to settle in the United States, he opened many temples and practice groups across the globe. He was known for his charismatic style and direct presentation of Zen, which was well tailored for the Western audience.

Seon or Sŏn Buddhism is the Korean name for Chan Buddhism, a branch of Mahāyāna Buddhism commonly known in English as Zen Buddhism. Seon is the Sino-Korean pronunciation of Chan an abbreviation of 禪那 (chánnà), which is a Chinese transliteration of the Sanskrit word of dhyāna ("meditation"). Seon Buddhism, represented chiefly by the Jogye and Taego orders, is the most common type of Buddhism found in Korea.