Arnold Sheldon Denker (February 20, 1914 - January 2, 2005) was an American chess player.

He was born in New York City, and was a promising boxer in his early years, before establishing himself as a leading rival to Samuel Reshevsky and Reuben Fine as strongest US chess player in the 1930s. He became US Champion in 1944, winning 14 games (including one against Fine), drawing 3 and losing none. The following year he played on board one in a US vs USSR radio match, losing both games to Mikhail Botvinnik, and in 1946 travelled to Moscow to lose both games against Vasily Smyslov in the return match. Also in 1946 he played at the very strong Groningen tournament, scoring 9.5/19 and securing draws against Botvinnik and Smyslov. Ken Whyld and David Hooper, writing in the Oxford Companion to Chess, note that Denker may have been unfortunate in that his best years came during World War II, when very little chess was being played.

Denker became an International Master in 1950 (the year the title was first awarded), and in 1981 FIDE made him an honorary Grandmaster. In later years, he was an important chess organiser, the driving force behind the Arnold Denker Tournament of High School Champions (held alongside the U.S. Open), and a FIDE official. He also continued to play chess, though at well below his earlier strength. His last FIDE Elo rating was 2293.

Denker wrote a number of chess articles and books, including The Bobby Fischer I Knew, and other stories (co-authored with Larry Parr, Hypermodern Press).

Denker died in 2005 after a brief illness.