Liberal Moon Jae-in is predicted to win the South Korean presidential vote, exit polls suggest.
Moon, 64, is expected to take over 40 percent of the vote.
The human rights lawyer favours a moderate policy on neighbour and rival, North Korea.
Why is there an election?
South Koreans have been voting in their presidential election, looking to move on from a corruption scandal that brought down former leader Park Geun-hye and shook the establishment.
The vote will end a months-long leadership vacuum. Park was ousted on charges of bribery and abuse of power and is in jail, awaiting trial.
Background on Moon Jae-in
Moon has criticised previous governments for failing to stop Pyongyang’s weapons development, and advocates dialogue while maintaining pressure and sanctions.
He also wants to reform powerful family-run conglomerates and boost spending to create jobs.
Who else was running?
Almost 20 points behind in the polls, centrist Ahn Cheol-soo voted in Seoul and said he would wait for the people’s “wise decision”.
If elected he, like Moon, was expected to avoid a lavish inauguration ceremony and start work immediately.
Third according to the polls, the ultra-conservative Hong Joon-Pyo cast his vote in the capital.
The outspoken former prosecutor, taken to task over sexism, argues for a harder line towards North Korea.
The winner is expected to be sworn in on Wednesday (May 10).