Mary Dolores Nichols (born 1945) is an American attorney and government official who has been the chairwoman of the California Air Resources Board (CARB) since 2007.

The CARB implemented a market-based cap-and-trade program to reduce the state's emissions of carbon dioxide and other greenhouse gases back to 1990 levels by 2020.

[16] She was part of California's delegation to the 2015 United Nations Climate Change Conference in Paris,[17] where she and other members of the Brown administration shared lessons on decarbonization with the rest of the world.

Nichols' leadership was likened to that of Captain David Farragut in the Battle of Mobile Bay, memorialized in the quote "Damn the torpedoes, full speed ahead!".

[21] Following the 2020 United States presidential election, Nichols was considered by President-elect Joe Biden for the role of administrator of the Environmental Protection Agency.

[22] Initially considered the frontrunner for the role, Biden instead nominated Michael S. Regan to the position, after 74 environmental justice activists based in California signed a letter urging him not to pick Nichols, arguing she had not done enough to assist low-income and minority communities.