Lansing, Robert (1864–1928), a United States lawyer and statesman. He succeeded William Jennings Bryan as Woodrow Wilson's secretary of state in 1915. Since Wilson made major policy decisions by himself and often executed them through his personal agent, Colonel Edward M. House, Lansing had little influence during the critical years leading to war with Germany. Wilson and Lansing worked in harmony, however, until 1919, when Lansing failed to show any enthusiasm for the proposed League of Nations. He resigned, at Wilson's request, in 1920.

Lansing was born in Watertown, New York. He graduated from Amherst College in 1886 and was admitted to the bar in 1889. After 1892 he served as United States counsel before several international arbitration courts. During 1914–15 Lansing was counselor to the State Department. After 1920 he resumed private law practice. The Peace Negotiations (1921) is an account of his relations with Wilson.