David O'Brien, UK
David O'Brien (born 28 January 1983 in Prescot, England) is a retired English pool swimmer who specialized in freestyle events. He competed in the 2004 Athens Olympic Games and trained at Stirling Swimming Club, under head coach Chris Martin. O'Brien qualified for the men's 4×200 m freestyle relay as a member of the British team, at the 2004 Athens Olympics. He finished sixth in the 200m freestyle from the Olympic trials in Sheffield, posting a relay entry time of 1:51.12. Teaming with Simon Burnett, Gavin Meadows, and Ross Davenport in the final, O'Brien swam a third leg and recorded a split of 1:49.05. He and the rest of the Brits missed the podium by 0.77 seconds behind the Italians.