Vassily Ivanchuk, also transliterated as Vasyl (or in Ukrainian: Василь Михайлович Іванчук , Vasyl Mykhaylovych Ivanchuk), born March 18, 1969, is a Ukrainian chess grandmaster. Ivanchuk has an Elo rating of 2787 on the FIDE October 2007 ratings list, making him number two in the world and Ukraine’s number one. He played board one on the victorious Ukraine team at the 2004 Calvia Chess Olympiad.

Ivanchuk reached chess world fame at the age of 21 when he won the Linares tournament in 1991. Fourteen players participated, eight of them rated top-ten of the world, including World Chess Champion Garry Kasparov, while the rest were all among the world’s top 50 players. It was a close call between Ivanchuk and Kasparov, but Ivanchuk won by half a point, and Ivanchuk defeated Kasparov in their individual game.

It was believed that Ivanchuk would become World Champion, but this has not yet happened, although he came close in 2002 when he reached the finals of the FIDE World Championship Knockout. Even though he has been consistently among the top 10 since 1989, ranked as high as number 2 on a few occasions, he has played poorly in matches which require a different approach than tournament play. Most chess fans blame this on his weak nerves and his tendency to blunder in critical positions.