Description from original post (created 2016-05-30 10:03):
The ultimate Marine.
Sergeant Major Avery Junior Johnson (SN: 48789-20114-AJ) was a Human senior non-commissioned officer who served with the UNSC Marine Corps during the Insurrection and Human-Covenant war. Avery Johnson was a highly trained Marine, serving with various combat units of the Naval Special Warfare Command, including the highly classified ORION Project.
Source:http://halo.wikia.com/wiki/Avery_Johnson