|Irish name||Gearóid Ó Braonáin|
|Height||1.83 m (6 ft 0 in)|
|**Inter County team apps and scores correct as of 23 August 2014.|
From a family of nine, he attended Belvedere College. At Belvedere he played Rugby, soccer, hurling and Gaelic Football.
Graduating from Maynooth College with undergraduate and masters degrees, he qualified as a school teacher and taught Irish and religion at St. Kevin's College, Ballygall Road, in Dublin 11. In November 2015 he was appointed Gaelic Games Executive at University College Dublin.
Brennan won his first Dublin Senior Football Championship medal with St Vincents in 2007 in the final against St Brigids at Parnell Park. He then went on to win the Leinster Senior Club Football Championship final against Tyrrellspass of Westmeath. Brennan was chosen as the Leinster club player of the year for his performances in the Leinster club championship with St Vincents.
Brennan madee his national league debut for Dublin against Tyrone on 3 February 2007. He was a member of Dublin team that won the 2007 O'Byrne Cup, playing against Laois at O'Connor Park in Offaly. The game finished on a scoreline of 1-18 to 2-13. He finished the tournament with a total of 0-04.
In 2008, he retired from Dublin's football panel, citing burnout and fatigue as his reasons. However, on July 30th 2008, he was named in Dublin's panel for the quarter-final and accepted a return. He was part of a victorious Dublin squad that won the All-Ireland Senior Football Championship in a match against Kerry. He won again with Dublin for a second time in 2013, scoring two points in the final against Mayo.
In October 2015, Brennan announced his retirement from Inter County football but will continue to play club football.
Brennan is a Catholic who has spoken about his faith in God. He has stated that while non-denominational schools may teach subjects such as science, Catholic schools "enable young students to have the skills to pray".
Brennan was praised for his "nonchalant delivery" of thanks to the "girlfriends and boyfriends of the players" after St Vincent's defeated Castlebar Mitchels in the 2014 All-Ireland Club Championship Final at Croke Park (a speech delivered in front of a live television audience). However just over a year later, Brennan wrote an op-ed for the Irish Independent arguing against the legalisation of same-sex marriage in that year's Marriage Equality referendum, which was ultimately carried in a 62% to 38% popular vote. His stance was criticised by others, including fellow GAA star Conor Cusack.
- Ger Brennan appointed Gaelic Games Executive at UCD www.ucd.ie, November 2015.
- Duncan, Pamela (20 January 2014). "Ger Brennan says time for young people to learn more about faith: Catholic Schools Week 2014 begins next Sunday, January 26th". The Irish Times.
- "Ger Brennan's 'inclusive' speech praised by gay rights groups". BBC News. BBC. 19 March 2014. Retrieved 19 March 2014.
- Brennan, Ger (15 May 2015). "Dublin football star Ger Brennan: Why I'm voting No". Irish Independent.
- Cullen, Adam (14 May 2015). "Conor Cusack challenges Dubs star Ger Brennan on opposition to same-sex marriage". Evening Herald.