Steel titan known for his dealmaking won six-month battle for rival Arcelor. The $34 billion merger created an industry behemoth that now accounts for 10% of world's production, putting it well ahead of Japan's Nippon Steel. Mittal owns 44% of combined $80 billion (sales) Arcelor-Mittal and is its chief executive. Mittal began his career working in the family's steelmaking business in India. Today Arcelor-Mittal operations span more than 60 countries and employ 330,000. Not content to dominate the steel industry, Mittal is branching out. Among his latest deals: spent $980 million for a 50% stake in Kazakh oil firm Caspian Investment Resources, a subsidiary of Russia's Lukoil. This Londoner is the UK's richest resident.

Son of a Boston cabdriver borrowed $200 from his uncle to sell newspapers at age 12. Made first fortune in trade shows. Created computer industry's premier show, Comdex, mid-1980s; ran 70% profit margin renting space for 15 cents a square foot and leasing it to exhibitors for up to $40 a square foot. Sold show to Japan's Softbank for $862 million in 1995. Then Las Vegas: bought old Sands casino for $128 million, demolished it to build the $1.5 billion all-suites Venetian casino resort and the 1.2-million-square foot Sands Convention Center. Changed the way Vegas does business by enticing conventioneers to Sin City midweek, taking emphasis off gambling. Sold suites for $250 a night, added high-end retailers, celebrity-chef restaurants. Old guard mocked him: "I loved being the outsider. I didn't care what those guys said." Took Las Vegas Sands public December 2004. Building $1.8 billion Palazzo resort adjacent to arch-rival Steve Wynn's Wynn Las Vegas. Big bet on Asia: opened $265 million Sands Macau casino May 2004, recouped entire investment in one year. Ramping up construction on Cotai Strip: $6 billion project will place 7 hotel-casinos on Macau's 2 islands, Taipa and Coloane. Cornerstone of project will be $1.8 billion Venetian Macau. Last May won coveted Singapore gaming license. Plans to build $3.5 billion Marina Bay Sands on 51-acre site with a view of the city's skyline.

Put up $15 million from his family's midsize construction firm to buy Christian Dior in 1985. Since then has built the world's largest luxury goods empire, LVMH Moet Hennessy Louis Vuitton, whose brands also include Dom Pérignon, Fendi and Tag Heuer Still heads the company, which is expanding rapidly in China, Russia and India. LVMH recently hired Frank Gehry to design a $127 million private museum in Paris. Son Antoine, 27, joined sister Delphine, 31, on LVMH's board last year. Arnault also set up an investment fund with his good friend Albert Frere in 2006; pair own two wineries together. In December opened his four-star hotel Le Cheval Blanc in ski resort Courcheval, France, where he often spends New Year's Eve. Said to be a skilled pianist.

Son of a railway worker. Ranks among world's 20 richest for first time. With help from then-wife Rosalía Mera, got start making gowns and lingerie in his living room 44 years ago. Business became one of world's most successful apparel manufacturers, $8.7 billion (2005 sales) Inditex. Group also owns 3,000 Zara retail stores in 64 countries. Ortega is chairman. Through his investment vehicles has invested in gas, tourism, banks and real estate; has properties in Madrid, Paris, London, Lisbon, plus luxury hotel and apartment complex in Miami. Reportedly owns a horse-jumping circuit and part of a soccer league. Shuns neckties.

Asia's richest resident. His fortune is centered on conglomerates Cheung Kong and Hutchison Whampoa. Through them Li is the world's largest operator of container terminals, a major supplier of electricity to Hong Kong, a cell phone provider, retailer and real estate developer. Also has a nearly $10 billion stake in Canadian oil company Husky Energy. Recently announced plans to donate one-third of wealth over time, calling it "his third son." Eldest son, Victor, helps run massive empire; son Richard struck out on his own in early 1990s. Once a poor immigrant, Li got his start selling plastic flowers in Hong Kong in the 1950s.

Took control of family fortune after his father, Kenneth Thomson, died last June. Had already succeeded his father as chairman of Thomson Corp., media conglomerate in which the family has a 70% stake, in 2002. Grandfather Roy founded the business in 1934. Company traded away traditional printed titles in order to move into software and electronic media for professionals, like Westlaw, a legal research tool. With his brother Peter also serves as cochair of family's investment concern, Woodbridge. Well known art collectors, the family bought $5 million worth of native North American art at auction last year, including a $1.8 million face mask, the highest amount ever spent on a single piece of native North American art. David said the family bought the collection in honor of his late father.