Who established the International Society for Krishna Consciousness (ISKCON)?

The correct answer is Bhaktivedanta Swami Prabhupada.

Key Points

• The International Society for Krishna Consciousness (ISKCON), or the Hare Krishna movement, was founded b His Divine Grace Acharya Bhaktivedanta Swami Prabhupāda in New York City in the year 1966.
• This Society includes major centers, temples, and rural communities, nearly one hundred affiliated vegetarian restaurants, thousands of local meeting groups (namahattas), a wide variety of community projects, and millions of congregational members worldwide.
• ISKCON belongs to the Gaudiya-Vaishnava sampradaya, a monotheistic tradition within the Vedic or Hindu culture.
• Philosophically it is based on the Sanskrit texts Bhagavad-Gita and the Bhagavat Purana, or Srimad Bhagavatam.
• These are the historic texts of the devotional bhakti yoga tradition, which teaches that the ultimate goal for all living beings is to reawaken their love for God, or Lord Krishna, the “all-attractive one”.
• ISKCON devotees chant God’s names in the form of the maha-mantra, or the great prayer for deliverance: "Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare/Hare Rama Hare Rama, Rama Rama, Hare Hare".

• Members of ISKCON practice bhakti-yoga in their homes and also worship in temples.

• They also promote bhakti-yoga, or Krishna Consciousness, through festivals, the performing arts, yoga seminars, public chanting, and the distribution of the society’s pieces of literature.

• ISKCON members have also opened hospitals, schools, colleges, eco-villages, free food distribution projects, and other institutions as a practical application of the path of devotional yoga.  

Source- https://www.iskcon.org/about-us/what-is-iskcon.php