Yegor Timurovich Gaidar () (also transliterated Gaider) (born March 19, 1956) is a Russian politician who served as acting Prime Minister briefly under President Boris Yeltsin in 1992 from June 15 to December 14. As the first post-Soviet Prime Minister, Gaidar advocated capitalist economic reform. Gaidar was the minister of economic development from 1991 until 1992, and minister of finance from February 1992 until April 1992. He was also the first deputy prime minister from 1991 until 1992 and again from September 1993 until January 1994.

Later in 1994, after leaving the government, he became a founding member and chairman of the Democratic Choice party. In 2000, he became a founding member and co-chairman, along with his longtime political ally Anatoly Chubais of the Union of Right Forces. In 2001 the Democratic Choice Party merged into the Union of Right Forces.

Yegor Gaidar is Arkady Gaidar's grandson.