John B. Timberlake (1777–1828) was a protagonist in the American political scandal known as the Petticoat affair. His wife Peggy O'Neill Timberlake was said to have had an affair with John Eaton, who became Secretary of War in President Andrew Jackson's cabinet. The scandal brought about the resignation of most members of Jackson's cabinet.

Timberlake was a purser in the United States Navy. During his initial service in the military, he fell into massive debt. In 1816, when he was 39 years old, he married Peggy O'Neill, who was 17. They moved into a house inWashington, D.C. provided by her father, across the street from his hotel and tavern called the Franklin House.

In 1818, the couple met the widowed United States Senator, John Eaton, then aged 28. Peggy was then 19 years old. John Eaton, recently elected and the youngest U.S. Senator, stayed at Franklin House.

Timberlake and Eaton became fast friends, and Timberlake confessed his financial problems. Eaton introduced a petition to the United States Senate to relieve Timberlake of debts collected while he was in service to the Navy. The Senate failed to act on his request and Timberlake slipped deeper into debt. He returned to the Navy, leaving his wife and their daughter, Mary Virginia Timberlake, behind in Washington. He returned for short periodic visits between voyages. In 1825 he fathered another daughter, Margret Rosa Timberlake.

Timberlake left for a four-year voyage on the USS Constitution. During his long absence, Peggy was said to have suffered a miscarriage, from a pregnancy that could only have resulted from another man. Although it was later rumored that he committed suicide, Timberlake died of pneumonia while on board ship in the Mediterranean Sea at age 51. Many people believed he had heard of his wife Peggy's alleged affair with Senator John Eaton and that this had been the reason for his alleged suicide.

Soon after Timberlake's death, Peggy and Eaton married. Their action brought widespread criticism, leading to what was called the Petticoat affair in President Andrew Jackson's administration.

John B Timberlake