Rhinelander Waldo (May 24, 1877 – August 13, 1927) was appointed the seventh New York City Fire Commissioner by Mayor William Jay Gaynor on January 13, 1910.

He resigned on May 23, 1911, less than two months after the deadly Triangle Shirtwaist Factory fire, to accept an appointment as the eighth New York City Police Commissioner.

He resigned from the Army in 1905 with the rank of captain and became New York's First Deputy Commissioner of Police in January 1906, at the age of 28.

[7] Another of his early acts as Police Commissioner was the appointment of three "Strong Arm" anti-vice squads and their commanders—one of whom, Charles Becker, was later executed for complicity in the July 1912 murder of the bookmaker Herman Rosenthal (shortly after Rosenthal had told the press of extortion by Becker and other police).

[10] After he was out of office, he stayed involved with political affairs and while Richard Enright was New York City Police Commissioner (appointed by the regular Democratic Mayor John Francis Hylan), Waldo served for a time as a special deputy but resigned in September 1924 to organize the Coolidge Nonpartisan League, a step that "marked his formal renunciation of Tammany Hall in favor of the Republican Party.

[10] On April 20, 1910, he was married to Virginia Otis Heckscher at the country house of artist Charles H. Ebert in Greenwich, Connecticut.