The Sassoon family were a wealthy Baghdadi Jewish dynasty, associated with finance, banking, capital markets, the exploration of oil and gas, Judaism, Conservative politics, opium trading and philanthropy. Their principal vehicles, Sassoon & Co. and J. Sassoon Financial Group LLC, are domiciled in Europe, Asia and North America.

The family was known as "the Rothschilds of the East" due to the immense wealth they accumulated in Asia. The family's businesses in China, India, and Hong Kong especially, were built to capitalise on the opium trade. As more family members gravitated toward London, they became prominent in England and were ennobled by Queen Victoria.

Although most biographical data about the Sassoons lists Baghdad, Iraq, as their place of origins, Daniel Gross, an American journalist, claims that the Sassoon family has their origins in Aleppo, Syria. They later moved to Mumbai, India, and then emigrated to China, England, and other countries. From the 18th century, the Sassoons were one of the wealthiest families in the world, with a corporate empire spanning the entire continent of Asia

The Hebrew word sasson (Hebrew: שָׂשׂוֹן) literally means "joy" or "gladness." The name of the family strongly implies a local, Mesopotamian origin. The family name of Sassoon is also commonly shared by many Kurdish families and tribes who all originate from the mountainous district of Sason (whence the family and tribal names), west of Lake Van, in upper Mesopotamia in modern Turkey. It is, however, possible that some Spanish Sephardi blood was mixed with the primarily Mesopotamian Jewish Sasoons.

Sassoon ben Salih (1750–1830) and his family were the chief treasurers to the pashas of Baghdad and Southern Iraq. His sons David (1792–1864) and Joseph Sassoon (1795–1872) fled from a new and unfriendly wāli, Dawud Pasha.

An important Jewish banker named Sassoon was hanged by the Ottoman Turks at the conclusion of the Siege of Kut al Amarah in April 1916. He may have been a member of David's branch of the family or of Joseph Sassoon's branch (see below).

In 1828 David first went to the Persian Gulf port of Bushehr and in 1832 to Bombay, India, with his large family. Over 39 years, with two wives, he fathered 14 children. In Bombay, he built the international business called David S. Sassoon, with the policy of staffing it with people brought from Baghdad. They filled the functions of the various branches of his business in India, Burma, Malaya, and east Asia. He cemented the family's dominant position in the Sino-Indian opium trade. The family's businesses in China, and Hong Kong especially, were built to capitalise on the opium business. His business extended to China, where Sassoon House (now the north wing of the Peace Hotel) on the Bund in Shanghai became a noted landmark, and then to England. In each branch, he maintained a rabbi. His wealth and munificence were proverbial; his philanthropy across Asia included the building of schools, orphanages, hospitals, and museums. On his death, tributes to him were made from across the continent by Muslims, Christians, Parsees, Jews, and Hindus.

Sassoon's eight sons also branched out in many directions. The Sassoon family was heavily involved in the shipping and the opium trade in China and India.