Cork born, one of six kids, O'Leary was schooled at Clongowes Wood College, along with the likes of the O'Reilly kids, Michael Smurfit, Tullow Oil's Aidan Heavey and former U2 head honcho Paul McGuinness.
Any silver spoon in his mouth was probably accidentally swallowed during one of his epic outbursts of swearing. The business mojo was clearly there, when he decided to whack up the price of batteries in his Walkinstown newsagents at Christmas. It was also the sign of someone who was as tough as nails. The accountant got close to aviation entrepreneur Tony Ryan and won his trust.
O'Leary was given the job of fixing the loss-making Ryanair.
His advice to Ryan was to close it down. But Ryan persevered and kept O'Leary on the case. He was made chief executive of the airline in 1994 and hasn't looked back.