He cultivated its brash, youthful arrogance as it battled regulators, governments and the Brussels, growing it from a small, upstart carrier on the edge of Europe, to its dominant low-cost carrier.
But the same traits that characterised the carrier for much of Mr O’Leary’s tenure as CEO also sometimes alienated Ryanair. But to Mr O’Leary, who owns almost 4pc of Ryanair, the old maxim that any publicity is good publicity seemed to hold true no matter what the circumstances.
Now the search – most likely to be an internal one – begins to find his successor. While he’ll oversee the group, a new chief executive will be in charge of the day-to-day.
Former Ryanair executive Peter Bellew, the Co Meath native who returned to the airline in 2017 after stepping down as chief executive of Malaysia Airlines, will be among the top contenders for the job.
He told disillusioned Ryanair pilots at Stansted in 2017 that Ryanair had lost its way. It was the aftermath of a pilot rostering debacle, and pilots were pushing for union recognition.
“I think the tone has gone very miserable. That’s the way I would see it, even in our head office. Everybody is very wounded by this,” he told the pilots of the rostering mess that resulted in thousands of flights being grounded.
Mr Bellew also said the airline needed to start treating people “like normal human beings”.
From Bettystown, Mr Bellew turns 54 next month.
Ryanair’s chief commercial officer David O’Brien (54), once a member of the defence forces’ Ranger wing, will also be a strong contender.
He’s been with the airline since the 1990s. He was the director of UK operations at Ryanair between 1998 and 2002, before being named its director of flight and ground operations.
Another executive likely to eye the top seat is Kenny Jacobs, Ryanair’s chief marketing officer.
A former executive at Moneysupermarket, the Cork native joined Ryanair in 2014, taking on responsibility for sales, digital marketing and customer service. He has also held positions at Tesco.
But whoever steers Ryanair from now on, they’ll have big boots to fill. And Mr O’Leary in the backseat.