Qassem al-Rimi, the new leader of Al-Qaeda's most feared branch, was among the Yemen-based group's founders and its military chief who has recruited a generation of fighters dedicated to jihad.
Also known as Abu Huraira al-Sanaani, the Yemeni was appointed military commander of Al-Qaeda in the Arabian Peninsula (AQAP) on its formation in 2009 in a merger between its branches in Saudi Arabia and Yemen.
Under his command, AQAP claimed a January attack on French satirical magazine Charlie Hebdo which killed 12 people, and was also behind an attempt to blow up a US commercial airliner on Christmas Day 2009.
In a video statement dated June 15, AQAP said its commanders have chosen Rimi as their new leader after a US drone strike killed his predecessor Nasir al-Wuhayshi in southeast Yemen last week.
Rimi and Wuhayshi announced the creation of Al-Qaeda in Yemen in 2007.
Washington, which labelled Rimi a "Global Terrorist" in May 2010, had offered a $5-million reward for any information leading to his capture or killing.
The US State Department says he "has played a key role in reviving the regional node of Al-Qaeda" and "has played an important role in recruiting the current generation of militants making up the Yemen-based AQAP".
According to several sources, Rimi was born in 1974 in the western province of Raymah and left home at 15.
He resurfaced as an instructor at an Al-Qaeda training camp in Afghanistan before the 2001 US invasion, says Gregory Johnsen in his book "The Last Refuge: Yemen, Al-Qaeda and the Battle for Arabia".
Rimi was in a group of fighters, including Wuhayshi, who operated under slain Al-Qaeda leader Osama bin Laden's direct supervision.
He was later extradited to Yemen and held in the same Sanaa prison with Wuhayshi, where he led Friday prayers and made fiery speeches against then-president Ali Abdullah Saleh, who was a close Washington ally in the war on Al-Qaeda.
In February 2006, Rimi was among a group of prisoners, including Wuhayshi, who made an audacious escape through a 44-metre (145-foot) tunnel between their cell and a nearby mosque, which they had dug with makeshift tools.
The jailbreak came as a boost to Al-Qaeda militants who reorganised their ranks in preparation for a merger three years later with their peers who were the target of a heavy crackdown by authorities in neighbouring Saudi Arabia.
Rimi's younger brother is in US custody at Guantanamo Bay, according to Johnsen.
In 2007, Rimi was linked to an attack that killed eight Spanish tourists in the eastern province of Marib.
He often appeared on videos issued by AQAP's media arm, Al-Malahem, urging jihad and encouraging young people to join his organisation.
But in December 2013, in a rare mea culpa, he apologised for a deadly Al-Qaeda attack on a Yemeni defence ministry hospital and said that the jihadist network was ready to pay blood money.
The attack killed 56 people, including many foreign doctors, and wounded 200.
"The attack was on the ministry of defence, it was not on the hospital," Rimi said.
"We told them (jihadists) to be cautious, not to enter the prayer place or the hospital. Eight of our brothers were cautious, and one did not. May Allah forgive him and have mercy on him," Rimi said at the time.
In a November 2014 audio message, which appears to have been his most recent media appearance, Rimi vowed to launch fierce attacks against Iran-backed Shiite Huthi rebels who have expanded across Yemen and are currently the target of a Saudi-led coalition air campaign.