Louisa Catherine Adams (née Johnson; February 12, 1775 – May 15, 1852) was the first lady of the United States from 1825 to 1829 during the presidency of her husband John Quincy Adams. She was born in England and raised in France. Her father was an influential American merchant, and she was regularly introduced to prominent Americans. After her family returned to England, she met John Quincy Adams in 1795, and the two began a tenuous courtship. They married in 1797 after being engaged for a year, beginning a marriage of disagreements and personality conflicts. She joined her husband on his diplomatic mission to Prussia, where she was popular with the Prussian court. When they returned to the United States, her husband became a senator and she gave birth to three sons. John was appointed minister to the Russian Empire in 1809, and they traveled to the Russian Empire without their two older sons, against Louisa's wishes. Though she was again popular with the court, she detested living in the Russian Empire, especially after the death of her infant daughter in 1812. She lived in the Russian Empire alone for a year while John negotiated the Treaty of Ghent. When he asked her to join him in 1815, she made the dangerous 40-day journey across war-torn Europe.

The Adamses lived in England for two years before returning to the United States when John was appointed Secretary of State. Louisa became a prominent cabinet wife and regularly hosted important guests in her home. She worked to build connections for her husband's 1824 presidential run, allowing for his victory. She was unsatisfied in the White House, where she became reclusive and grew distant from her husband. She instead took to writing, producing plays, essays, poems, and an autobiography. She wished for retirement after her husband lost re-election, but he was elected to the United States House of Representatives. She took a more active interest in politics, supporting abolitionism and greater rights for women in society. She was widowed in 1848, and she had a stroke in 1849 that left her with limited mobility. She died on May 15, 1852, at the age of 77, and Congress adjourned for her funeral, the second time a woman was honored in this way.

She was the only foreign-born first lady of the United States until 2017, when Melania Trump became first lady. Her tenure as first lady is not as well studied as other parts of her life, due to her reclusiveness and the limited records she kept at the time. Still, she is generally rated in the upper half of first ladies by historians.

Louisa Catherine Johnson was born in London on February 12, 1775. She was the second daughter of American merchant Joshua Johnson and Englishwoman Catherine Nuth. The Johnsons were an influential family in American politics, with Louisa's paternal uncle Thomas Johnson being one of the signers of the 1774 Continental Association. Little is known of her mother's life prior to her marriage. Louisa's parents may have only married ten years after her birth, potentially making Louisa the only first lady of the United States to be born out of wedlock. She lived a comfortable life as a child in which all of her needs were seen to.

Louisa's father supported American independence, and the Johnsons left England in 1778 in response to the American Revolutionary War. They moved to Nantes, France, where they lived for the next five years. While in France, Louisa attended a Catholic boarding school. She performed well in school, becoming proficient in music and literature, and she learned to speak French fluently. She also practiced Catholicism. Such was her immersion in French that she was later forced to relearn English. She was also versed in Greek and Latin. The Johnsons lived in luxury, even when they did not have the financial means to do so. Their home in France was a mansion that came to be known as "The Temple of Taste".

The Johnsons returned to England and settled in Tower Hill, while Louisa was placed in a London boarding school. She was teased for her French mannerisms, and the Catholicism that she had learned in France caused conflict with her Anglican religious education in England. Her self-esteem suffered, and she kept a distance from her peers. She was sent to be educated by John Hewlett, an Anglican minister and a family friend of the Johnsons. Hewlett became a strong influence on her upbringing, encouraging her intellectualism. The Johnsons suffered financially in 1788, and she was pulled out of school to be educated by a governess.

Johnson's father was appointed the American consul to Great Britain in 1790, and she often assisted in entertaining prominent guests. Among these guests, the Johnson daughters looked for potential suitors, as they were pressured to marry a prominent young man. John Quincy Adams became one such guest in 1795 in his capacity as an American diplomat. He began showing up each day, and only later did the Johnsons realize that he intended to court Louisa, initially believing that his interest was in her older sister Nancy. Only after he complied with a joking request to write her a romantic poem did she consider him a potential suitor.

Johnson and Adams began a courtship, though it was intermittent, and they did not immediately take to one another. Both had previously expressed interest in other potential partners. It was their talents and prestige that eventually drew them to one another. Adams in particular was taken by Johnson's aptitude for singing and music. This pairing also caused a rivalry between Louisa and her older sister, who was jealous for the man she thought would court her.