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- Russian surname (Russian Гайда́р), a pseudonym of Arkady Gaidar which was taken as a last name by his descendants:
- Arkady Gaidar (real name Arkady Golikov, 1904–1941), Soviet writer of children's stories.
- Timur Gaidar (1926–1999), Soviet admiral, Arkady's son
- Yegor Gaidar (1956–2009), former acting Prime Minister of Russia, Timur's son
- Maria Gaidar (born 1982), Russian activist of the political youth movement "DA!", daughter of Yegor Gaidar