Elizabeth Rebecca Laird (December 6, 1874 – March 3, 1969) was a Canadian physicist who chaired the physics department at Mount Holyoke College for nearly four decades.

[9] She studied at the Humboldt University of Berlin from 1898 to 1899, working with Max Planck and under Emil Warburg on time lag in magnetization.

[1] She was the first woman accepted by Sir J. J. Thomson to conduct research at Cambridge University's Cavendish Laboratory where she worked in the Summer 1905 and Spring 1909.

Laird presented several top secret reports on her findings to the National Research Council, taught army and navy personnel, and took her turn monitoring the unheated observation station on the university's campus.

[2] In 1945, she was made an honorary professor of physics at the University of Western Ontario and continued working upon the absorption of ultra-high frequency radiation by tissue.

[2][4][9] Physicist A.D. Misener said that Laird was "the rare combination of a conscientious and productive research worker and an inspiring and able teacher.