Vojislav Koštunica (born 24 March 1944) is a Serbian former politician who served as the last president of FR Yugoslavia from 2000 to 2003 and as the prime minister of Serbia from 2004 to 2008.

Koštunica won the 2000 Yugoslav presidential election as a candidate of a broad alliance Democratic Opposition of Serbia (DOS), which led to overthrow of Slobodan Milošević and the withdrawal of international sanctions against Yugoslavia. He strictly opposed cooperation with the International Criminal Tribunal for the former Yugoslavia (ICTY) and his party left the coalition government in protest at the decision to extradite Slobodan Milošević to the ICTY. After the 2003 Serbian parliamentary election, the first elections after the dissolution of DOS and assassination of Prime Minister Zoran Đinđić, Koštunica formed a minority government with the support of Milošević's Socialist Party of Serbia and became the head of government. He was one of the crucial figures in the adoption of the first constitution of an independent Serbia, as well as for declaring Serbia a neutral country. During his second government (2007–2008), he opposed signing the Stabilisation and Association Agreement (SAA) with the European Union, leading to the fall of the government after a year and the early elections won by pro-European parties.

He was one of the founders and the first president of the Democratic Party of Serbia from its creation in 1992 until 19 March 2014, when he resigned as party president and retired from active politics after his party failed to reach the 5% threshold to enter the Parliament on March 16 elections for the first time in its history. In October 2014, he left the party after disagreements with the new party leadership over what he saw as their abandonment of the policy of political neutrality. In November 2014, he was one of the founders of the right-wing eurosceptic "Statehood Movement of Serbia".

Koštunica was born on 24 March 1944 in his family home in Belgrade, Yugoslavia. As a youth he went by the nickname 'Voja'. His paternal family descends from Jovan Damjanović, who originated from the village of Koštunići. He was educated in Belgrade, where he finished elementary school, and graduated from the Second Belgrade High School in 1962. Koštunica enrolled in the University of Belgrade's Faculty of Law the same year, graduating in 1966. He earned his master's degree in 1970 and his Ph.D. in 1974 with his thesis Institutionalized Opposition in the Political System of Capitalism.

Koštunica was an assistant at the faculty from 1970 until 1974, when he left due to a political purge at the university for criticising the communist regime of Josip Broz Tito. After his expulsion, Koštunica worked at the Institute of Social Sciences, and from 1981 at the Institute for Philosophy and Social Theory, where he engaged in the protection of human rights, specifically in the defence of freedom of thought and expression.

Koštunica was a founding member of the Democratic Party (DS) in 1989. He left the Democratic Party in 1992 over opposing views in leadership and formed the Democratic Party of Serbia.

Supported by both nationalists and liberals, the Democratic Opposition of Serbia backed him in the 2000 presidential election against incumbent Slobodan Milošević. Koštunica received 50.2 percent of the vote in the first round of voting, just a few thousand votes over the threshold needed to win outright. Milošević disputed the results of the first round, claiming that Koštunica had only received 49 percent of the vote and a runoff was required. The Otpor movement, a student-led movement to oust Milošević and install free and fair elections, organized a protest where thousands of Serbians participated in strikes and took over the Belgrade capital and forced Milošević to accept the results and step down as president. Koštunica then assumed the presidency. He was the last president of the Federal Republic of Yugoslavia. Koštunica opposed the extradition of his predecessor, to the Hague Tribunal, and voiced opposition to the court.

Koštunica became prime minister in March 2004 as the head of the new minority government, albeit with the support of the Socialist Party of Serbia.