Dhirajlal Hirachand Ambani, also known as Dhirubhai, 28 December 1932, - 6 July 2002, was an Indian rags-to-riches business tycoon who founded Reliance Industries in Mumbai with his cousin. Ambani took his company (Reliance) public in 1977, and by 2007 the combined fortune of the family (sons Anil (Anil Ambani) and Mukesh (Mukesh Ambani)) was 60 billion dollars, making the Ambanis the second richest family in the world, next to the Walton family. Dhirubhai has been one among the select Forbes billionaires and has also figured in the Sunday Times list of top 50 businessmen in Asia.

Dhirubhai started off as a small time worker with Arab merchants in the 1950s and moved to Mumbai in 1958 to start his own business in spices. After making modest profits, he moved into textiles and opened his mill near Ahmedabad. Dhirubhai founded Reliance Industries in 1958. After that it was a saga of expansions and successes.

Reliance, acknowledged as one of the best-run companies in the world has various sectors like petrochemicals, textiles and is involved in the production of crude oil and gas, to polyester and polymer products. The companies refinery at Jamnagar accounts for over 25% of Indias total refining capacity and their plant at Hazira is the biggest chemical complex in India. The company has further diversified into Telecom, Insurance and Internet Businesses, the Power Sector and so on. Now the Reliance group with over 85,000 employees provides almost 5% of the Central Governments total revenue.

In 1986 after a heart attack he has handed over his empire to his two sons Anil and Mukesh. His sons are carrying on the successful tradition of their father.