Date of birth: 18/09/93
This attacking midfielder has come through the Rovers ranks from the Academy to the fringes of the first team.
A star performer from the Under-18s run to the Youth Cup final of 2011-12, John has progressed quickly at the club. Making his senior debut at the end of the 2012-13 as a substitute in the 1-1 draw with Birmingham City.
A regular at international level for the Republic of Ireland's Under-21 squad.
January 2014 saw O'Sullivan join Conference side Southport on a month-long loan deal.