The Democratic Party (DP; Korean: 민주당; RR: minjudang), formerly the Democratic United Party (DUP; 민주통합당) until 2013, was a liberal political party in South Korea, and for the duration of its existence the country's main opposition force.

On 15 December 2011, the Democratic Party, which had been the main opposition in the 18th Assembly, merged with the minor Citizens Unity Party to form the DUP. The Democratic United Party had strong connections with the Federation of Korean Trade Unions. The forming of the party took place against the background of the forthcoming April 2012 legislative election, in which the centre-left opposition sought to defeat the ruling Saenuri Party.

At the party's first congress on 15 January 2012, the DUP voted Han Myeong-sook chairwoman of the supreme council. Han was from 2006 to 2007 South Korea's first and so far only female Prime Minister. Han Myeong-sook vowed to retaliate against the Supreme Prosecutors' Office of South Korea for hiding corruption and malpractice by the Lee Myung-bak administration. The New Politics Alliance for Democracy followed the Party's position.