John Gretton Willink, or commonly known as "Jocko" Willink, is a former United States Navy officer who served in the Navy SEALs as the commander of SEAL Team 3's Task Unit Bruiser.

Willink fought in the battle against the Iraqi insurgents in Ramadi and was awarded with the Silver Star and Bronze Star medals, and promoted to the rank of lieutenant commander. After retiring from the army, Jocko has become an American author, podcaster, and a motivational speaker who has inspired millions of people with his story.

Willink co-authored the books Extreme Ownership and The Dichotomy of Leadership with fellow retired SEAL Leif Babin, and co-founded Echelon Front, a management consulting firm who provides leadership courses, strategic advising and workshops, with a mission of building and training high-performance winning teams.