Helen Violet Bonham Carter, Baroness Asquith of Yarnbury, DBE (15 April 1887 – 19 February 1969), known until her marriage as Violet Asquith, was a British politician and diarist. She was the daughter of Herbert Asquith, Prime Minister from 1908–1916, and later became active in Liberal politics herself, being a leading opponent of appeasement, standing for Parliament and being made a life peer. She was also involved in arts and literature. Her illuminating diaries cover her father's premiership before and during World War I and continue until the 1960s.
She was Sir Winston Churchill's closest female friend, apart from his wife, and her grandchildren include the actress Helena Bonham Carter.
Violet Asquith grew up in a heavily political environment, living in 10 Downing Street, at the time her father occupied it, and socialising with the key political figures of her day. She did not go to school, but was educated at home by governesses, and later sent to Paris and Dresden to improve her languages. Her mother, Helen Kelsall Melland, died of typhoid fever when Violet was only four. Her stepmother was Margot Tennant. Her best friend when she was young was Venetia Stanley, who had an affair with her father. Violet quarreled constantly with her formidable stepmother Margot, much to her father's distress; in later life she admitted that despite their differences, she respected Margot for her absolute devotion to Asquith.
Violet Bonham Carter's father served a long and influential term as Prime Minister, especially during the peacetime portion of his premiership (1908–1914) when he presided over the People's Budget and the House of Lords limiting Parliament Act 1911. He was Prime Minister at the beginning of World War I and then headed a coalition with the Conservative Party beginning in May 1915 until his resignation in December 1916. The Liberal Party split thereafter between followers of Asquith and of David Lloyd George, who had replaced him as Prime Minister. As the Liberal Party fell on hard times in the 1920s, she became a tireless defender of her father and his reputation, beginning by campaigning for him at the 1920 Paisley by-election.