Sergeant Major William Gainey served as the first Senior Enlisted Advisor to the Chairman (SEAC) from 1 October 2005 through 25 April 2008.

General Peter Pace selected Army Command Sergeant Major William Gainey to serve as the first Senior Enlisted Advisor to the Chairman ("SEAC"), beginning 1 October 2005. Gainey had more than 30 years of active-duty experience including an extensive background in joint operations. He had most recently served as the command sergeant major of III Corps and Fort Hood, Texas, from 9 May 2003 until 30 September 2005. He served as Senior Enlisted Advisor to the Chairman until he retired on 25 April 2008.