Ukrainian comedian Volodymyr Zelensky has won a run-off election to become the country's next president with more than 70 percent of the vote, exit polls suggest.
The polls give him more than 70 percent support. He dominated the first round of voting three weeks ago when 39 candidates were on the ticket.
Mr Zelensky, 41, is best known for starring in a political satirical drama called Servant of the People in which his character accidentally becomes Ukrainian president. He ran under a political party with the same name as his show.
"I will never let you down," Mr Zelensky told supporters on Sunday.
"While I am not formally president yet, as a citizen of Ukraine I can tell all post-Soviet countries: 'Look at us! Everything is possible!'"
If polls are correct, he will be elected for a five-year term.
He challenged incumbent president Petro Poroshenko, a billionaire businessman elected after an uprising overthrew the country's previous, pro-Russian government.
Polls gave Mr Poroshenko, who has been in power since 2014, 25 percent of the vote. Mr Poroshenko has admitted defeat but told supporters gathered in Kiev that he will not leave politics.
"The outcome of the election leaves us with uncertainty [and] unpredictability," he said after exit polls were released.
"I will leave office but I want to firmly stress - I will not quit politics," he added.
Ukraine's president holds significant powers over the security, defence and foreign policy of the country.
The country's choice was between an experienced politician with five years as president on his CV and a comedian wielding little more than a blank sheet of paper. That so many people have opted for Mr Zelensky is a humiliation for Mr Poroshenko.
The result appears to be a massive protest vote. With no previous political experience, Mr Zelensky's campaign focused on his difference to the other candidates rather than on any concrete policy ideas.
Despite this, he won the first round with more than 30 percent of the vote - almost double what Mr Poroshenko got when he finished in second place with 15.95 percent.
The hard work will come when they have to start fleshing out what are at the moment vague policies.