Nicholas Ernest de Firmian is an American chess player who received the FIDE title of Grandmaster (GM) in 1985. He is a three-time U.S. chess champion, winning in 1987, 1995, and 1998. He also tied for first in 2002, but Larry Christiansen won the playoff. He is also a chess writer, most famous for his work in writing the 13th, 14th, and 15th editions of the important chess opening treatise Modern Chess Openings. He was born in Fresno, California.

The US Chess Championship is an invitational tournament organized by the United States Chess Federation to determine the country's chess champion. It is the oldest national chess tournament. The event originated as a challenge match in 1845, but the champion has been decided by tournament play under the auspices of the USCF since 1936. The tournament has fluctuated between a round-robin tournament and a Swiss system. From 1999 to 2006, the championship was sponsored and organized by the Seattle Chess Foundation and featured a larger body of competitors, made possible by the change to a Swiss-style format. After the Foundation withdrew its sponsorship, the 2007 and 2008 events were held in Stillwater, Oklahoma, still as a Swiss system, under tournament director Frank K. Berry. Rex Sinquefield's Saint Louis Chess Club has hosted the championship since 2009. Since 2014, the championship has used a round-robin format.