The Munster outside half, who has appeared on each of the three most-recent Lions tours, has scored a record 1,138 points in Europe's premier club competition.
O'Gara has made 91 Heineken Cup appearances, scoring an average of 12.5 points per game and winning European titles in 2006 and 2008.
The Ireland star is joined by fellow Lions Geordan Murphy, Josh Lewsey, Brian O'Driscoll, Rob Howley, Martin Johnson and David Wallace in a European All Star XV.
All five of those men have played alongside O'Gara in Lions colours, with O'Driscoll a tourist in 2001, 2005 and 2009; Wallace a Lion in 2001 and 2009; Howley a Lion in 1997 and 2001, and Murphy and Lewsey Lions Test players in 2009.
Johnson has the most impressive Lions record of the lot, having toured in 1993, 1997 and 2001 and skippered the squad on both his second and third tours.
England's World Cup winning captain has an impressive European pedigree too, leading Leicester Tigers to Heineken Cup glory in 2001 and 2002.
Murphy, Wallace and Lewsey are also double Heineken Cup winners, while O'Driscoll and Howley both have one title to their name.
The team was selected by a nine-man panel that included no fewer than five Lions, with Sir Ian McGeechan, Lawrence Dallaglio, Ieuan Evans, Donal Lenihan and Stuart Barnes giving their verdict alongside Fabien Galthie, Michael Lynagh, Jacques Verdier and Stephen Jones of The Times.
The panel also announced a ERC European Fair Play Award, with the honour going to yet another Lion in Wales openside Martyn Williams.
A triple Lions tourist just like O'Gara, the Cardiff Blues star was seen by the panel as the embodiment of the values of the game of rugby in European club competitions and an inspirational role model.
ERC European Dream Team
15 Geordan Murphy (Leicester Tigers)
14 Josh Lewsey (London Wasps)
13 Brian O'Driscoll (Leinster)
12 Yannick Jauzion (Toulouse)
11 Vincent Clerc (Toulouse)
10 Ronan O'Gara (Munster)
9 Rob Howley (London Wasps)
1 Christian Califano (Toulouse)
2 William Servat (Toulouse)
3 Sylvain Marconnet (Stade FranÃ§ais Paris)
4 Martin Johnson (Leicester Tigers)
5 Fabien Pelous (Toulouse)
6 Rocky Elsom (Leinster)
7 David Wallace (Munster)
8 Anthony Foley (Munster)
Bold denotes Lion