Mary Nielsen Cook (born June 8, 1951) was a counselor in the general presidency of the Young Women organization of the Church of Jesus Christ of Latter-day Saints (LDS Church) from 2007 to 2013.

In April 2008, Dalton succeeded Tanner as Young Women General President and selected Cook as her first counselor.

Born in Midvale, Utah, Mary Nielsen earned undergraduate and graduate degrees from Brigham Young University in audiology, speech pathology, and education.

The Cooks later lived in Hong Kong, China while Richard served as a member of the presidency of the church's Asia Area.

In April 2008, Dalton succeeded Tanner as Young Women General President and selected Cook as her first counselor.