The current Leader of the Opposition is Siniša Hajdaš Dončić, president of the SDP, who took up the role on 21 September 2024, after winning the elections for the head of the Social Democratic Party.

[citation needed] Vladimir Šeks led the Croatian Democratic Union in opposition until the election of Ivo Sanader in 2000.

In the Ninth assembly of the Croatian Parliament (2016–2020), the parties in Sabor that include the opposition are: Zoran Milanović led the opposition until the November 2016 election of Davor Bernardić as the new leader of the Social Democratic Party.

In the Tenth assembly of the Croatian Parliament (2020–24), the parties in Sabor that included the opposition were: In 2020, Zlatko Komadina headed SDP until the election of Peđa Grbin.

In the eleventh assembly of the Croatian Parliament (2024–), the parties in Sabor that include the opposition are: In 2024, Siniša Hajdaš Dončić was elected the new head of the SDP.