Alexandra Kosteniuk (born April 23, 1984) is a Russian chess Grandmaster and the 12th Women's World Chess Champion (2008-2010).

Kosteniuk learned to play chess at the age of five after being taught by her father. In 2001, at the age of 17, she reached the final of the World Women's Chess Championship, where she narrowly lost to Zhu Chen. In 2004 Alexandra became the European women's champion by winning the tournament in Dresden, Germany.

This victory let Alexandra become the tenth woman in history to receive the highest title of the World Chess Federation, FIDE - men's grandmaster. In 2005 Alexandra won the Russian Women's Championship finishing with a score of +7 =4 -0. In August 2006, she became the first Chess960 (Fischer random) women's world champion after winning over Germany's top female player Elisabeth Pähtz 5.5-2.5.

She defended that title successfully in 2008 by taking over Kateryna Lahno 2.5-1.5. Alexandra's greatest success so far has been to win the Women's World Chess Championship 2008, beating in the final the young Chinese prodigy Hou Yifan, with a score of 2.5-1.5. In the Women's World Chess Championship, 2010 she was eliminated in the third round by Ruan Lufei and thus lost her title.

Alexandra together with her Russian national team won two European championships (2007, 2009) as well as the World Chess Olympiad 2010.

Kosteniuk's mottos are "chess is cool" and "beauty and intelligence can go together". With these as a backdrop, Kosteniuk has been promoting chess in the capacity of a fashion model and ambassador of chess in order to spark interest in the game around the world.

She has been named Champion for Peace for the Organization Peace & Sports and promotes peace in the world through the game of chess. Alexandra is very active on the internet with her trademarked nickname "Chess Queen" and her web site is www.chessqueen.com .