Gary Milo Ridley, PE (September 29, 1945 – December 21, 2022) was an American engineer and civil servant from the state of Oklahoma most notable for concurrently serving as the state's Secretary of Transportation, Director of the Department of Transportation, and the Director of the Oklahoma Turnpike Authority between 2009 and 2013.

As Director, Ridley was responsible for managing the Department through the crisis caused by the I-40 bridge disaster, and the reconstruction in the summer of 2002.

[2] In October, 2009, former Transportation Secretary Phil Tomlinson retired as Director of the Oklahoma Turnpike Authority effective November 1, 2009.

[2] Governor of Oklahoma Brad Henry appointed Ridley as his second Secretary of Transportation following the resignation of Phil Tomlinson in 2009.

[citation needed] On November 29, 2010, Governor-elect Mary Fallin announced that she would retain Ridley as Secretary of Transportation in her Administration.