21. Dieter Schwarz & family
Net worth: £12.0 billion
Age: 77
As owner of Schwarz-Gruppe, Dieter Schwarz runs budget supermarket chain Lidl and German hypermarket chain Kaufland, and is the richest man in Germany.
20. Kirsten, Finn and Jorn Rausing
Net worth: £12.9 billion
These are the third-generation heirs to the Tetra Pak packaging fortune. The company has an annual turnover of £11.3 billion, and employs over 30,000 people.
19. Leonardo Del Vecchio
Net worth: £12.9 billion
Age: 81
Italian businessman Del Vecchio is founder and chairman of Luxottica Group, which is the world's largest producer of glasses and lenses. The group has over 75,000 employees and over 7,000 stores worldwide.
18. Sri and Gopi Hinduja
Net worth: £13.0 billion
The pair, who reside in the UK, are one-half of the so-called "Fantastic Four," a set of siblings in their seventies who run conglomerate company Hinduja Group, which is based in London. The firm owns Indian automotive manufacturer Ashok Leyland.
17. David and Simon Reuben
Net worth: £13.1 billion
David and Simon Reuben are British businessmen and philanthropists. The brothers were born in India, and made their fortune in metals trading and property development.
16. Georg and Maria-Elisabeth Schaeffler and family
Net worth: £14.1 billion
Age: 52 & 75
Georg Schaeffler owns 80% of industrial manufacturing company Schaeffler Group, while his mother owns the other 20%. The company produces rolling element bearings for automotive, aerospace, and industrial uses.
15. Giovanni Ferrero and family
Net worth: £15.1 billion
Age: 52
Giovanni Ferrero has run confectionery company Ferrero SpA, best known for its Nutella chocolate spread and its Ferrero Rocher chocolates, since the death of his brother Pietro Ferrero in 2011.
14. Alain and Gerard Wertheimer
Net worth: £16.4 billion
Age: 68 & 66
The brothers run the House of Chanel, the world-famous fashion brand. The business came into the family after their grandfather, Pierre Wertheimer, became an early business partner with Gabrielle Bonheur Chanel, the house's founder.
Queen Elizabeth is pictured in 2015 presenting the pair with a trophy after their racehorse won the Elizabeth II Stakes Race run at Ascot.
13. The Mulliez family
Net worth: £16.6 billion
The Mulliez family derive their wealth from the Arnaud Group, a French international retail group and corporation based in Croix, France, founded by Gerard (pictured). The group has nearly 270,000 employees across 15 countries.
12. George Soros
Net worth: £17.1 billion
Age: 86
George Soros is a Hungarian-born American fund manager, philanthropist, and major political donor. He is known as "The Man Who Broke the Bank of England" because of his short sale of $10 billion of British Pound Sterling during the 1992 Black Wednesday currency crisis.
11. Axel Dumas
Net worth: £17.3 billion
Age: 46
Dumas has controlled fashion house Hermès International since 2013. The Dumas family retain a 70% stake in the billion-dollar company.
10. The Oeri / Hoffmann family
Net worth: £18.4 billion
The Oeri-Hoffman clan consists of the descendants of the founders of Swiss pharmaceutical giant Roche. They retain a controlling stake in the firm, despite their lack of operational roles.
9. The Henkel family
Net worth: £18.7 billion
The Henkel family run a conglomerate of the same name which manufactures products including Persil washing powder. Founded in 1876, the company is based in Düsseldorf, Germany.
8. Stefan Persson, Lottie Tham & family
Net worth: £21.7 billion
Age: 69 & 67
The Swedish siblings own a large chunk of the H&M fashion fortune, which their father founded. Persson is chairman and CEO, while Tham owns a 5% share of the brand.
7. Bernard Arnault
Net worth: £23.6 billion
Age: 67
Bernard Jean Étienne Arnault is chief executive of luxury goods firm LVMH, the umbrella company for brands including fashion house Louis Vuitton and champagne house Moët & Chandon. He is the richest man in France.
6. Liliane Bettencourt
Net worth: £25.0 billion
Age: 94
Bettencourt is the "grand dame" of L'Oreal. Bettencourt and her children own 33% of the cosmetics company. She suffers from dementia, which means her children now run her business affairs.
5. Stefan Quandt and Susanne Klatten
Net worth: £25.4 billion
Age: 50 & 54
The reclusive pair are heirs to the BMW fortune. Their father was Herbert Quandt, the industrialist who turned BMW into an industrial giant.
4. Sergey Brin
Net worth: £26.1 billion
Age: 43
Soviet-born computer scientist Brin is the co-founder of Google. He is the president of Google's parent company Alphabet Inc., and the 12th richest person in the world.
3. Karl Albrecht Jr, Beate Heister & family
Net worth: £27.1 billion
The pair are the children — and heirs to the fortune — of the late Karl Albrecht, who co-founded discount supermarket chain Aldi with his brother. Albrecht, who passed away in 2014, based his supermarket chain's success on a no-frills strategy similar to Wal-Mart's in America, and there are now over 10,000 stores in 18 countries.