Sheikh Mohamed bin Zayed Al-Nahyan, the first Gulf leader to strike a deal normalising relations with Israel, has long been seen as a strongman who has driven the UAE's rise to diplomatic prominence.
In a 2009 note to US President Barack Obama leaked by WikiLeaks, former American ambassador Richard Olson said the royal -- better known as MBZ -- was "the man who runs the United Arab Emirates".
Despite a low profile, and his apparent reluctance to speak in public, his ambition has been on display in recent years as the UAE built its profile as a regional player.
The country -- a collection of emirates better known for its skyscrapers, palm-shaped islands and opulent mega attractions -- has in short order built a nuclear power program and sent a man to space.
And in July it joined another elite club by sending a probe to Mars, to mark the 50th anniversary of its unification.
Named crown prince of Abu Dhabi in November 2004, Sheikh Mohamed is the third son of Sheikh Zayed bin Sultan Al-Nahayan -- the revered founder of the UAE.
With his brother Sheikh Khalifa the nation's president, he serves as deputy commander of the armed forces and chairman of the Executive Council of Abu Dhabi, which controls the emirate's substantial finances.
While the glitzier emirate of Dubai has had to develop its tourism and services industries to make its fortune, Abu Dhabi sits on 90 percent of UAE oil production.
Born in the capital on March 11, 1961, Sheikh Mohamed was sent to military school in Britain, where he graduated from the famed Sandhurst Royal Military Academy in 1979.
He rapidly rose through the ranks of the armed forces to become air force commander, deputy chief of staff and finally chief of staff in January 1993 and a year later was promoted to the rank of general.
Described by diplomats as Abu Dhabi's strongman, Sheikh Mohamed has forged links in world capitals, particularly in the West.
He is widely believed to have taken the decision to deploy boots on the ground in Yemen in 2015 as part of a Saudi-led military campaign against Iran-backed Shiite Huthi rebels.
The Yemen war marked the first protracted military campaign abroad for the UAE and the first time it had to contend with military casualties, with dozens of Emirati soldiers killed.
The coalition has been denounced for air strikes, including on markets and hospitals, that have caused heavy civilian casualties since intervening in Yemen in March 2015.
The UAE, which largely exited the conflict last year, has also been accused of running secret prisons across southern Yemen. It denies the accusations.
Although the crown prince does not often speak in public -- he left the November 2017 inaugural speech of the Louvre Abu Dhabi to Dubai ruler Mohammed bin Rashid -- his reach into the political sphere cannot be underestimated.
Under his leadership, Abu Dhabi has fostered trade and political ties across the region -- including, to a limited extent, with Shiite Iran -- but has sided with the US against Tehran's nuclear programme and with Saudi Arabia on its role in the mainly Sunni Arab world.
Sheikh Mohamed also took the lead on a staunch no-mercy domestic security policy.
Observers believe it was he who masterminded an unprecedented clampdown on Islamists in the UAE, with dozens handed lengthy jail terms over charges of ties to extremists.
At the same time, he crafted for the UAE a reputation of tolerance that contrasts with its conservative neighbours.
In 2017, he announced that Abu Dhabi's Grand Mosque, also known as Sheikh Zayed mosque after his father, would change names to become the "Mariam Umm Issa" (Mary, Mother of Jesus) mosque as a means to "consolidate bonds of humanity between followers of different religions".
An avid football fan, MBZ is president of the local club in the oasis of Al-Ain, his father's hometown and the second largest city in Abu Dhabi.
He has also been spotted cycling through the capital in shorts and a helmet.
A keen hunter and a poetry enthusiast, he is married to fellow royal Sheikha Salama bint Hamdan Al-Nahyan -- the couple has four sons and five daughters.