Net worth: $26.3 billion

Age: 59

Country: India

Industry: Petrochemicals, oil, and gas

Source of wealth: Inheritance/self-made; Reliance Industries

Mukesh Ambani took over as chairman of Reliance Industries when his father, the company's founder, died in 2002. The enormous industrial conglomerate has interests in energy, petrochemicals, textiles, natural resources, retail, and, more recently, telecommunications.

Ambani is the richest person in India and owns a 27-story Mumbai mansion that cost $1 billion to build.

And if Ambani's projections for India's economy prove correct, expect that net worth to soar— it has already grown by $6.3 billion in the last year. Five years years ago, Ambani predicted that India would grow from a $1.4 trillion economy in 2011 to a $30 trillion economy by 2030 — a bullish estimate considering that India's GDP today stands at $2.4 trillion.