Mike Cohn is the owner of Mountain Goat Software and is recognized as one of the contributors to the invention of Scrum. He is one of the founders of the Scrum Alliance and is a Certified Scrum Trainer. He is a trainer on Scrum and agile software process techniques and helped popularize Planning poker which he provides as a free online planning tool.

From Wikipedia.com (http://en.wikipedia.org/wiki/Mike_Cohn)