Tierney Thys (born 1966) is an American marine biologist, science educator, and National Geographic explorer.^[1][2] In 1988 she earned a degree in biology from Brown University, and in 1998 she earned a doctorate in biomechanics.^[3] She was formerly the director of research at the Sea Studios Foundation.^[4] She was also the science editor for The Shape of Life and director for Strange Days on Planet Earth.^[1] She has also written, narrated and produced short films.^[5] Since 2000 she and her colleagues have been studying the giant ocean sunfish (mola).^[3] In 2004 she was named a National Geographic "Emerging Explorer".^[1] She has since joined National Geographic expeditions and developed a National Geographic children's television conservation series.^[1]

She has given two TED talks, "Swim with the giant sunfish", and "The secret life of plankton".^[4] As of 2015 she was producing an online series for TEDed titled Stories from the Sea.^[5]

A chapter of Earth Heroes: Champions of the Ocean, by Fran Hodgkins, is about her, and she is briefly profiled in Girls Research!: Amazing Tales of Female Scientists.^[1][6] Science Methods and Process Skills: Meet Tierney Thys, National Geographic Emerging Explorer, by Kathy Cabe Trundle, was published by National Geographic School Publishing in 2011.^[7] A virtual aquarium in the educational game Animal Jam is named after her.

She is a certified pilot and diver.^[8]