Castrén is the surname of a Finnish family. Notable members include:

• Aarne Castrén (1923–1997), Finnish Olympic sailor
• Arthur Castrén (1866–1946), Finnish politician
• Garth Castrén (born 1939), Finnish diplomat
• Inga-Brita Castrén (1919–2003), Finnish theologian
• Jalmar Castrén (1873–1946), Finnish politician
• Jonas Castrén (1850–1922), Finnish lawyer and politician
• Kaarlo Castrén (1860–1938), Finnish lawyer and politician, briefly Prime Minister of Finland
• Klaus Castrén (1923–2011), Finnish diplomat
• Matthias Castrén (1813–1852), Finnish ethnologist and philologist
• Matilda Castren (born 1995), Finnish professional golfer
• Mauno Castrén (1931–2021), Finnish diplomat
• Natalia Castrén (1830–1881), Finnish culture personality and salon hostess
• Urho Castrén (1886–1965), President of the Supreme Administrative Court of Finland, briefly Prime Minister of Finland

• All pages with titles containing Castren