Isidoro Alvarez, the man who turned his uncle's small tailoring service into a retail empire, has died at the age of 79 in Madrid.
The second-gen entrepreneur, who inherited 15% of El Corte Inglés from his uncle, was rushed to hospital last week after complaining of breathing difficulties and died early on Sunday morning from a subsequent heart attack.
Alvarez spent more than 60 years working in the family's department store chain, founded by uncle Ramón Areces in 1940, and is largely credited with transforming the business into a global operation.
El Corte Inglés posted sales of €14.2 billion in 2013, and with more than 90,000 staff is one of the country's largest employers. In 2013 the firm posted profits of €174 million.
The news comes just one week after another Spanish family business giant, Emilio Botin, chairman of Banco Santander, also died from a heart attack at the age of 79. The banking group has since announced that daughter Ana Botin will assume the role of chairman.
Alvarez was born in the northern province of Asturias in 1935 and at 23 years old took a leading position in the family business. In 1989, the second-gen was named president following the death of his uncle.
During his career, Alvarez acquired huge swathes of real estate in order to open superstores in central city locations, and began offering lucrative insurance and travel services to customers.
Recently, the group has been hit by Spain's economic downturn and was forced in 2013 to restructure €5 billion in debt. El Corte Inglés also sold a 51% stake of its financing wing to Santander for €415 million.
Alvarez had a personal net worth of $919 million according to Bloomberg's Billionaires Index.
Spanish media reports have predicted that Dimas Gimeno Alvarez, nephew of Isidoro and the current director general, is likely to take over as chairman. The 38-year-old appointed non-family advisor Manuel Pizarro in 2013 to bring outside expertise to the secretive group.
Spain's economy minister, Luis de Guindos, called Alvarez “one of the great businessmen of this country”.
El Corte Ingles operates primarily in Spain and Portugal, and has ambitions to enter the Italian market.