The founder of Penneys, Arthur Ryan, has died at the age of 83, the company has confirmed.
Mr Ryan founded the first shop 50 years ago in Dublin, where it traded as Penneys, after being recruited by the Weston family to open a discount clothes retailer.
Penneys - which had to change its name to Primark for European markets outside Ireland because JC Penney owned the copyright to the name - has gone on to have 370 stores in 12 countries, employing 75,000 people.
Mr Ryan was chief executive until 2009, before stepping into the chairman's seat until his death.
He personally oversaw much of the expansion, including opening the first British Primark in 1973.
The boss also helped cement Primark's name on the UK high street, buying 120 former Littlewoods branches in 2005.
George Weston, the chief executive of Penneys' parent company, Associated British Foods, said: "Arthur Ryan will be remembered as one of the great giants of retailing. When my grandfather, Garfield Weston, and uncle, Galen Weston, recruited Arthur to run Penneys in 1969 with only one store in Dublin, they knew they were hiring an exceptional trader.
"But what three generations of Westons learned over the following decades was that Arthur was also a great leader and business builder, driven by a relentless desire to delight his customers.
"He made fashion accessible to all and his legacy looms large.
"He built a phenomenal world-class retailer, the foundations of which will always belong to Ireland."
Penneys chief executive Paul Marchant said: "He challenged us all to be the best we can be. His drive and passion was always shown alongside great humility, integrity and support for our people.
"Arthur remained deeply connected to the business and the customer, regularly visiting stores and walking the shop floor.
"Those of us who worked closely with him will cherish his friendship and wisdom and he will be hugely missed."