Sonia Gandhi (Hindi: [ˈsoːnɪjaː ˈɡaːndʱiː], Italian: [ˈsɔːnja ˈɡandi]; née Maino [ˈmaino]; born 9 December 1946) is an Indian politician of Italian origin. She is the longest serving president of the Indian National Congress, a social democratic political party, which has governed India for most of its post-independence history. She took over as the party leader in 1998, seven years after the assassination of Rajiv Gandhi, her husband and a former Prime Minister of India, and remained in office until 2017 after serving for twenty-two years. She returned to the post in 2019 and remained the President for another three years.

Born in a small village near Vicenza, Italy, Gandhi was raised in a Roman Catholic family. After completing her primary education at local schools, she moved for language classes to Cambridge, England, where she met Rajiv Gandhi, and later married him in 1968. She then moved to India and started living with her mother-in-law, the then-Prime Minister of India, Indira Gandhi, at the latter's New Delhi residence. Sonia Gandhi, however, kept away from the public sphere, even during the years of her husband's premiership.

Following her husband's assassination, Gandhi was invited by Congress leaders to lead the party, but she declined. She agreed to join politics in 1997 after much pleading from the party; the following year, she was nominated for party president, and elected over Jitendra Prasada. Under her leadership, the Congress went on to form the government post the 2004 elections in coalition with other centre-left political parties. Gandhi has since been credited for being instrumental in formulating the United Progressive Alliance (UPA), which was re-elected to power in 2009. Gandhi declined the premiership following the 2004 victory; she instead led the ruling alliance and the National Advisory Council.

Over the course of her career, Gandhi presided over the advisory councils credited for the formation and subsequent implementation of such rights-based development and welfare schemes as the right to information, Food Security Bill, and MGNREGA, as she drew criticism related to the Bofors scandal and the National Herald case. Her foreign birth has also been a subject of much debate and controversy. Gandhi's active participation in politics began to reduce during the latter half of the UPA government's second term owing to health concerns. She stepped down as the Congress president in December 2017, but returned to lead the party in August 2019. Although she has not held any public office in the government of India, Gandhi has been widely described as one of the most powerful politicians in the country, and is often listed among the most powerful women in the world.