Belfast-born McKillen worked in his family exhaust repair business before moving into property in the 1980s. He developed shopping centres including the Jervis Centre, in Dublin before building up a portfolio of valuable assets outside Ireland.
After the crash, McKillen took a landmark case to successfully prevent the transfer of his 2.1bn in loans, on almost 70 properties around the globe, to Nama. His Irish-focused Clarendon Properties — owned with Tony Leonard and which controls the Jervis Centre and Powerscourt Townhouse — had 500m worth of properties and about 360m in debt before the crash.
McKillen was at the centre of a high-profile row with the British billionaire Barclay brothers over the ownership of the Claridges hotel group. He sold his 36pc stake to Qatari royal family-backed Constellation Group for close to 800m, which was more than enough to clear his debts. He continues to manage the hotels and was paid 3.5m for the job last year. McKillen's other interests include the biodynamic Chateau la Coste vineyard in Provence.
His children have inherited his knack for business. Paddy Jnr owns a string of Dublin's trendiest bars and hotels, including the Dean Hotel and Peruke and Periwig, while Dean McKillen sold his Hollywood home to Calvin Klein for $25m.