John Lacey (born 12 October 1973) is an Irish rugby union referee and former player. He is a retired Irish rugby union player who played full-back/wing for Munster, until retiring in 2007 and becoming an international rugby union referee, representing the Irish Rugby Football Union, in 2011.
His refereeing days began in the Munster Schools Cup competitions, before being appointed to some key European club games in 2008, as well as gaining promotion to the IRB Assistant Referee Panel in 2009. In 2010, he was on the IRB referee panel for the 2010 IRB Junior World Championship in Argentina – refereeing 4 fixtures including the semi-final between South Africa and New Zealand.
During 2014 fitness testing he was recorded as the fastest rugby referee on the IRB panel.
Lacey was part of the refereeing panel at the 2015 Rugby World Cup.
He refereed the Scotland–England match in the 2016 Six Nations Championship.