Dan Ahearn (né Daniel William Ahearne; April 12, 1888 – December 20, 1942) was an Irish and later American track and field athlete and a member of the Irish American Athletic Club. He competed for the U.S. Olympic team in the 1920 Summer Olympics. He was born in Athea, Ireland and was the younger brother of Tim Ahearne. Ahearn immigrated with his family to the United States in 1909 where the "e" from Ahearne was dropped. He was not naturalized before 1912 because he was not allowed to compete in the 1912 Summer Olympics when he did not hold the U.S. citizenship.