Below are some facts about Ghannouchi, who said he will remain as caretaker president until early elections are held.
* He was born on Aug. 18, 1941 in Sousse, a coastal town about 100 km (62 miles) south of the Tunisian capital.
* He studied economic sciences at university and as part of his studies spent time on a secondment to the finance ministry in former colonial power France.
* He was part of a team which entered government when Ben Ali was appointed prime minister by Tunisia's previous president, Habib Bourguiba.
* When Bourguiba left office in 1987 after Ben Ali had doctors declare him medically unfit, Ben Ali became president and appointed Ghannouchi to the cabinet. He was first finance minister and then minister for international cooperation and investment.
* Ben Ali appointed Ghannouchi as his prime minister on Nov. 17, 1999.
* Ghannouchi took a high profile role during the unrest which preceded Ben Ali's departure. It was the prime minister who announced the sacking of the interior minister earlier this week, and Ghannouchi also gave interviews to the international media defending Tunisia's handling of the protests.