Osama Al-Juwali, Head of the Military Council in Zintan, was given the defense job as part of a cabinet line-up in which secularist liberals were dominant and which had no key roles for the Islamists who have been making a bid for power since Gaddafi's fall.
Al-Juwali is a former Officer in the Libyan military whose forces from Zintan played a crucial role in the offensive on Tripoli which ended Gaddafi's rule in August. He has not previously been seen as a contender for the defense job.
But he appeared to have staked a claim to the post after forces under his command on Saturday captured Saif al-Islam, the son of the former Libyan Leader who is wanted for prosecution by the International Criminal Court.
Al-Juwali is a former teacher who later joined the military. He is also the nephew of a former Libyan Deputy Central Bank Governor.
The Defense Minister's role had been coveted by Islamists, who after being persecuted for years under Gaddafi assumed powerful roles in the chaos which followed his fall.
In other appointments, Fawzi Abdelali was named Interior Minister, and Ashour Bin Khayyal Foreign Minister.
Abdelali is a militia leader from the western city of Misrata, Libya's third-largest.
Khayyal is a former Diplomat who served under Gadhafi as Libyan Ambassador to Canada in the 1980s. He later joined the Libyan opposition.
For more information, check Al-Defaiya Issue # 6/2011