Karin Hildur "Kajsa" Ollongren (Dutch: [ˈkɑisaː ˈʔɔlɔŋgreːn] ⓘ; Swedish: [ˈkâjsa ˈɔ̌lːɔnɡreːn] ⓘ; born 28 May 1967) is a Dutch-Swedish politician who served as Minister of Defence from 10 January 2022 to 2 July 2024.

Alexander Ollongren, a Dutch East Indies-born astronomer and computer scientist, and his Swedish wife Gunvor Lundgren.

Her portfolio as alderwoman was extensive, including economic affairs, seaport, airport, participation, art, culture, local media, monuments and the city centre.

She also became the second of the cabinet's three Deputy Prime Ministers, serving alongside Hugo de Jonge and Carola Schouten.

Following the 2021 general election, Ollongren (D66) and Annemarie Jorritsma of the People's Party for Freedom and Democracy (VVD) led the initial exploratory talks of the government formation.

[12] Ollongren had introduced a bill days before that would require Dutch defence companies to produce for the Royal Netherlands Army in case of a potential war.