Volodymyr Zelenskiy swept to power three years ago promising to end a war with Moscow-backed separatists in eastern Ukraine. He now faces a Russian invasion that could result in the overthrow of his government and the end of Ukrainian democracy.
As Russia rained missiles down on Ukrainian cities including Kyiv on Thursday, Zelenskiy appealed to all citizens to defend Ukraine, saying weapons would be given to all who wanted them.
"Russia treacherously attacked our state this morning, as Nazi Germany did during World War Two, " Zelenskiy told Ukrainians in a national address, reports Reuters.
"Russia has embarked on a path of evil, but Ukraine is defending itself and won't give up its freedom, no matter what Moscow thinks."
It is a disastrous outcome for Zelenskiy, a 44-year-old former comic actor whose increasingly insistent calls over the past two years for NATO to admit Ukraine, an ex-Soviet republic, have infuriated Russian President Vladimir Putin.
Moscow had demanded that NATO promise never to take in Ukraine, a country of huge geopolitical, historic and cultural importance to Russia, a demand rebuffed by the West. Putin on Monday rejected Ukraine's right to exist as an independent state, saying it is effectively part of Russia.
In recent weeks, Zelenskiy has drawn praise from Western leaders for his composure and his appeals to Ukrainians not to panic as Russia massed up to 150,000 troops near the border.
He also criticised foreign embassies and Ukrainian businessmen for leaving Ukraine for security reasons, and renewed his call for companies to stay put, saying they risked inadvertently helping Putin's efforts to destabilise Ukraine.
SERVANT OF THE PEOPLE
But Zelenskiy is an unlikely wartime leader. He shot to fame in a popular television series "Servant of the People" in which he played an honest school teacher who is elected president and outwits crooked lawmakers and shadowy businessmen.
Winning the presidency by a landslide in April 2019, he pledged to tackle the corruption that has blighted Ukraine's transition from communism to democracy. But Russia has always posed the biggest challenge to his aspirations to build a modern, democratic and stable European country.
His Servant of the People party - named after the TV series - won a big majority in a July 2019 parliamentary election and Zelenskiy initially pursued confidence-building measures with Russia in eastern Ukraine, including prisoner exchanges.
But that minor thaw did not last long. Russia, which in 2014 seized Ukraine's Crimean peninsula, continued to back armed separatists battling Kyiv's forces in the mainly Russian-speaking Donbass region of eastern Ukraine in a conflict that Zelenskiy says has claimed at least 15,000 lives to date.
Risking Moscow's ire, Zelenskiy courted Western leaders, including US President Joe Biden at talks in the White House on Sept 1, 2021.
"Everyone should understand...that we are at war, that we are defending democracy in Europe and defending our country, and therefore you cannot just talk to us with phrases about reforms," Zelenskiy said a June 2021 interview.
"Every day we prove that we are ready to be in the (NATO) alliance more than most of the countries of the European Union."
'A NEW FACE'
Zelenskiy rode a wave of public discontent with Ukraine's corrupt political elite to victory over wealthy businessman Petro Poroshenko in 2019.
Asked by Reuters ahead of that election how he differed from other presidential hopefuls, Zelenskiy pointed to his face, saying: "This is a new face. I have never been in politics."
"I have not deceived people. They identify with me because I am open, I get hurt, I get angry, I get upset... If I'm inexperienced in something, I'm inexperienced. If I don't know something, I honestly admit it."
But despite his promises to curb the influence of tycoons in politics, Zelenskiy has had to fend off suspicion that he is a puppet of Ihor Kolomoisky, an oligarch whose TV channel aired "Servant of the People".
Zelenskiy was also drawn unwittingly into US politics after a phone call in which then-President Donald Trump tried to get him to investigate his Democratic rival Biden over business deals in Ukraine.
The Democrat-led US House of Representatives impeached Trump after an inquiry concluded he had withheld military aid from Ukraine in order to influence Kyiv. Trump denied wrongdoing and the Republican-controlled US Senate later acquitted him.