Daniel John Cook Jr. (August 12, 1926 – July 3, 2008) was a sports writer for the San Antonio Express-News for 51 years.

[1] He is most notable for making the phrase "the opera ain't over till the fat lady sings" into common use.

Cook wrote his first sports column for the San Antonio Express-News on November 29, 1956.

[1] In 1976, Ralph Carpenter of Texas Tech University coined "the opera ain't over until the fat lady sings".

[7][1] On March 1, 1996, Cook was inducted into the San Antonio Sports Hall of Fame for his work as a columnist and a broadcaster.