Jadranka Kosor (Pakrac, 1. srpnja 1953.), hrvatska političarka, 9. predsjednica Vlade Republike Hrvatske.
Godine 1995. postala je potpredsjednica HDZ, a te je godine izabrana i u Hrvatski sabor. Potpredsjednicom HDZ-a bila je do 1997. godine. Do 2000. obnašala je dužnost potpredsjednice Sabora. Od 1999. do 2002. predsjednica stranačke Zajednice žena "Katarina Zrinski". U Sabor je ponovno ušla 2000., a dvije godine kasnije izabrana je za zamjenicu predsjednika HDZ-a na VII. Općem saboru HDZ-a. Na parlamentarnim izborima 2003. godine ponovno je izabrana za zastupnicu u Hrvatskom saboru u I. izbornoj jedinici (Zagreb), ali je svoj mandat stavila u mirovanje jer je imenovana za potpredsjednicu Vlade Republike Hrvatske zaduženu za socijalna pitanja, te ministricom obitelji, branitelja i međugeneracijske solidarnosti. Dužnost potpredsjednice Vlade i ministrice u vladama premijera Sanadera obnašala je do 2009. godine.
Na predsjedničkim izborima 2005. godine, kao kandidatkinja HDZ-a izgubila je u drugom krugu od Stjepana Mesića. Nakon ostavke premijera Sanadera, 3. srpnja 2009.
Predsjednik Republike povjerio joj je mandat za sastavljanje Vlade. Dana 6. srpnja 2009. nova Hrvatska vlada na čelu s Jadrankom Kosor dobila je povjerenje većine saborskih zastupnika u glasovanju na kraju zasjedanja.
Nekoliko mjeseci nakon odlaska s mjesta predsjednice Vlade RH, na stranačkim izborima dana 20. svibnja 2012., u prvome je krugu izbora ispala treća, ispod Kujundžića i Karamarka, koji su ušli u drugi krug izbora za novog predsjednika HDZ-a.
Prije proglašenja novog predsjednika, poslije ponoći 20. svibnja, napustila je dvoranu Vatroslava Lisinskoga u kojoj su se održavali izbori.
Jadranka Kosor (born 1 July 1953) is a Croatian politician who served as Prime Minister of Croatia from 2009 to 2011, having taken office following the sudden resignation of her predecessor Ivo Sanader. Kosor was the first woman to become Prime Minister of Croatia since independence.
Kosor started working as a journalist, following her graduation on the Zagreb Law School. During the Croatian War of Independence, she hosted a radio show dealing with refugee problems and disabled war veterans. She joined the centre-right Croatian Democratic Union (HDZ) in 1989 and quickly climbed up the party hierarchy. In 1995 she was elected party vice-president and was elected to serve in Parliament for the first time. After the death of President and longtime HDZ leader Franjo Tuđman, Kosor supported Ivo Sanader's successful party leadership bid in 2000. Three years later, her party won the parliamentary election and Kosor became the Minister of Family, Veterans' Affairs and Inter-generational Solidarity in the Sanader I and, later, Sanader II cabinet, during which time she served as Deputy Prime Minister as well. In the 2005 presidential election she ran as a representative of HDZ, but lost to incumbent President Stipe Mesić in the second round. After the abrupt resignation of Sanader, Kosor managed to form a functioning parliamentary majority and was approved to her new post as Prime Minister in July 2009, also becoming leader of her party. Kosor was the party's candidate for Prime Minister in the 2011 general election, but HDZ lost in a landslide over the centre-left Kukuriku coalition, led by the Social Democratic Party. Kosor handed power to the new Prime Minister, Zoran Milanović, in December 2011.
As Prime Minister, Kosor failed to commit to structural reforms and introduced new taxes as a response to the ongoing economic crisis. During her tenure, she strongly advocated a zero tolerance policy to political corruption and organized crime. This uncompromising stance, along with the new criminal code passed before her term began, opened the door to unprecedented efforts to combat corruption. This resulted in numerous arrests of influential business-people and politicians from across the political spectrum, although most of them members of HDZ, which severely damaged the party's reputation. The discoveries made by prosecutors were far-reaching and criminal charges were even raised against former Prime Minister and Kosor's own political mentor Ivo Sanader, who would later be charged with 10 years in prison for criminal activity and abuse of power. In foreign policy, Kosor and her Slovenian counterpart Borut Pahor were successful in solving the long-standing border dispute and she is credited with successfully finishing the negotiating process of the Croatian accession to the European Union. On 9 December 2011, she and President Ivo Josipović signed the Treaty of Accession in Brussels. A moderate conservative, Kosor ran for another term as party leader after losing the election, however was defeated by the more conservative Tomislav Karamarko. After months of criticizing his leadership and the new party platform, she was expelled from HDZ by the party's High Court for damaging the party's reputation.