Abhisit Vejjajiva is the English-born, Oxford-educated 46-year-old who as prime minister led Thailand's Democrat Party into July's general election but quickly conceded defeat to the main opposition Pheu Thai party.
Young and photogenic, though not known as particularly dynamic, he has a reputation for "clean politics".
His government faced major protests in 2010 which paralysed parts of the capital and left more than 90 people dead.
Distinctly upper-class, Mr Abhisit hails from a wealthy family of Thai-Chinese origin. Both his parents were medical professors.
He was born in the British city of Newcastle in August 1964 and educated at England's top public school, Eton. He then went on to gain a degree in politics, philosophy and economics (PPE) at Oxford University.
Mr Abhisit's support is drawn mainly from southern Thailand and from Bangkok's educated middle-classes. He has had less success in attracting the support of working class and rural Thais.
In 1992, Mr Abhisit joined Thailand's oldest party, the Democrats, and at the age of 27, entered parliament as one of its youngest ever members. Having tried and failed to become party leader in 2001, he eventually got the post in 2005.
Championing a raft of populist policies, Mr Abhisit campaigned under the slogan "Putting People First".
The Democrat Party failed to win power in national elections in 2007 - the first since the military coup in 2006 that ousted then Prime Minister Thaksin Shinawatra. Instead, Mr Thaksin's allies won.
Months of political pressure by anti-Thaksin protesters followed, including a week-long sit-in at Bangkok's two airports, which shut down air traffic and crippled the tourism industry.
In December 2008 the Constitutional Court found the ruling party, led by Mr Thaksin's allies, guilty of electoral fraud and banned it.
This enabled Mr Abhisit to form a new government and become the next prime minister without calling elections.
At age 44, he became the country's youngest prime minister in more than 50 years.
His government has faced major protests; the first in 2009.
A year later, in March 2010, Mr Abhisit was spirited away to a barracks when red-shirted opposition protesters marched on Bangkok, denouncing him as an illegitimate leader.
In May that year, a military crackdown brought an end to the demonstrators' occupation of the city's commercial district.
More than 90 people died in the course of the protests, which hit the economy hard.
While not entirely ditching the liberal reforms of "Thaksinomics" - a term used to refer to the economic set of policies of the exiled former leader - Mr Abhisit has argued for a more statist approach.
Among other things, Mr Abhisit has advocated free healthcare, a higher minimum wage, and free education, including textbooks and milk for nursery-school children.
He has also been a consistent campaigner against corruption.
When Mr Thaksin called a snap election in February 2006, Mr Abhisit's campaign pitch was that he was "prepared to become a prime minister who adheres to the principle of good governance and ethics, not authoritarianism".
Later that year, he opposed the military when it overthrew Mr Thaksin in a coup.
"We cannot and do not support any kind of extra-constitutional change, but it is done. The country has to move forward and the best way forward is for the coup leaders to quickly return power to the people and carry out the reforms they promised," he said at the time.
He also said he expected high standards of probity from his party and any government he led.
Going beyond the current transparency rules for Thai MPs, he said he would require all future Democrat Party representatives to declare their assets and any involvement in private companies.
However, that has not shielded his government, or party, from corruption allegations, including claims of a cover-up of illegal donations by a petrochemical firm.
But the main chink in the Abhisit armour, apart from the impression that his good looks tend to outshine his sometimes rather bland political pronouncements, has been his failure to win the popular vote.
His acceptance of defeat in the July 2011 election has done nothing to change that.
Before entering parliament, Mr Abhisit had a brief academic career. After Oxford, he taught at Thailand's Chulachomklao Royal Military Academy.
Later, he returned to Oxford to study for a Master's degree. He then taught economics at Thammasat University before studying law at Ramkhamhaeng University.
Mr Abhisit's family is a circle of accomplished individuals. One of his two sisters is a professor of child psychology, while the other is a leading Thai author.
Mr Abhisit's wife is a dentist-turned-mathematics lecturer at Chulalongkorn University. They have two children.