|Irish name||Briain Ó hAonasa|
29 August 1969|
Birr, County Offaly, Ireland
|*Inter County team apps and scores correct as of 11:41, 30 June 2014.|
Born in Birr, County Offaly, Hennessy first excelled at hurling in his youth. He first came to prominence on the inter-county scene when he first linked up with the Offaly minor team, before later joining the under-21 side. He made his senior debut during the 1990-91 National League and immediately became a regular member of the team. During his career he won one National Hurling League medal on the field of play.
His retirement came following the conclusion of the 1995 championship.
- All-Ireland Senior Club Hurling Championship (2): 1995, 1998 (sub)
- Leinster Senior Club Hurling Championship (4): 1991, 1994, 1997, 1999
- Offaly Senior Club Hurling Championship (5): 1991, 1994, 1997, 1999, 2000
- All-Ireland Senior Hurling Championship (1): 1994
- Leinster Senior Hurling Championship (2): 1994, 1995
- National Hurling League (1): 1990-91
- Leinster Under-21 Hurling Championship (1): 1989
- All-Ireland Minor Hurling Championship (1): 1987
- Leinster Minor Hurling Championship (1): 1987