Mary J. Ruwart, PhD (October 16, 1949 – ) is a research scientist and libertarian speaker, writer, and activist. She was a leading candidate for the 2008 Libertarian Party presidential nomination and is the author of the award-winning international bestseller Healing Our World.
In March 2008, in response to an informal draft effort by a group of Libertarian Party activists, Ruwart announced her candidacy for the Libertarian presidential nomination in the 2008 election. She lost the nomination to Bob Barr on the sixth ballot at the 2008 Libertarian National Convention on May 25, 2008. Despite tying with Barr on the third and fourth ballots and taking the lead on the fifth, she ultimately lost after third-placed candidate Wayne Allyn Root threw his support behind Barr. Root later received the vice-presidential nomination.