Robert Bacon (July 5, 1860 – May 29, 1919) was an American athlete, banker, businessman, statesman, diplomat and Republican Party politician who served as the 39th United States Secretary of State in the Theodore Roosevelt administration from January to March 1909. He also served as Assistant Secretary of State from 1905 to 1909 and Ambassador to France from 1909 to 1912.

Bacon was a native of Boston, Massachusetts and attended Harvard College. While a student at Harvard, he starred in athletics, captaining the football team, rowing crew, and winning events in boxing and track. He befriended future president Theodore Roosevelt, leading to a lifelong friendship and professional relationship. After graduation, he became an investment banker with the firm of Lee, Higginson & Co. before joining J.P. Morgan & Co. in New York.

As Secretary of State, Bacon pressed Roosevelt's interests in the United States Senate to ratify treaties with Colombia and the new nation of Panama to resolve disputes over the Panama Canal. He continued to advance United States interests in Latin America after leaving office, conducting a tour of the region for the Carnegie Endowment for International Peace and publishing a treatise arguing for better relations with South America.

Bacon was a leader in the movement for military preparedness following the outbreak of the First World War, establishing training programs for potential soldiers and officers prior to American entry to the war. In 1916, he narrowly lost the Republican primary for United States Senator from New York to William M. Calder. He was commissioned as a major in the United States Army in 1917 and served under General John Pershing in France. Pershing appointed Bacon to a major role as the chief American liaison to British General Headquarters. Bacon returned to the United States following the war but died from complications following surgery less than two months after his arrival in New York City.

Robert Bacon was born on July 5, 1860, in Jamaica Plain, Massachusetts, and raised in the Beacon Hill neighborhood of Boston. His father, William Benjamin Bacon, was a Boston merchant who founded Daniel G. Bacon & Company with his elder brother and served as the Boston agent for Baring Brothers. The Bacon family had early colonial roots and settled in the town of Barnstable on Cape Cod. His mother, Emily Crosby Low, was ill for most of his childhood and died when he was eleven years old.

After attending the Hopkinson School in Boston, Bacon was enrolled at Harvard College in 1876, shortly after his sixteenth birthday. At Harvard, he was a star athlete and popular classmate, captaining the football team and freshman baseball team, rowing seven in the crew, winning a heavyweight boxing championship, and winning both the quarter-mile and hundred-yard dash. He was also president of the glee club, chief marshal of his class day celebration, and a member of the A.D. Club and Delta Kappa Epsilon. He graduated as the youngest member of the class of 1880, which included future President Theodore Roosevelt and was called "Bacon's class." Roosevelt and Bacon were close friends and sparring partners during their time at Harvard. Following graduation, he completed a tour of the world, traveling west through Japan, China, India, and the Mediterranean.

Bacon began his career at the investment bank of Lee, Higginson & Company in Boston; Henry Lee Higginson was a family friend and neighbor on Beacon Hill. In 1883, he accepted an offer to join the firm of E. Rollins Morse, where he handled some of the Boston business of J. P., Morgan.

In 1894, Bacon accepted an offer to become a partner in J.P. Morgan & Co. in New York City, cancelling plans to relocate to France for his children's education. He would remain with the firm until his resignation in 1903. As a junior partner to J. P. Morgan, he was one of the most trusted lieutenants in the firm and often led the American business while Morgan was in Europe.