Lady Antonia Fraser (Pinter), CBE (born August 27, 1932, as Antonia Margaret Caroline Pakenham) is a British author of history and novels, best known for writing biographies. She is the daughter of the Earl and Countess of Longford (Frank and Elizabeth Pakenham), who were both eminent writers, Labour supporters and Catholic converts. Their eight children became child converts to the Catholic Church. As the daughter of an Earl, Antonia Fraser is entitled to be called "Lady Antonia."

Lady Antonia was educated at Lady Margaret Hall, Oxford. Her first major work was Mary, Queen of Scots (1969). She followed it up with various other biographies, including Cromwell, Our Chief of Men (1973). She won the Wolfson History Award in 1984 for The Weaker Vessel, a study of women's lives in 17th century England. She was President of English PEN from 1988 to 89, and was Chairman of its Writers in Prison Committee.

In addition, she writes detective novels, with the most popular involving a character named Jemima Shore. A television series based on these stories was aired in the UK in 1983.

More recently, Lady Antonia published The Warrior Queens, the story of various military royal women since the days of Boadicea and Cleopatra. In 1992 she published The Six Wives of Henry VIII. It was published only a year after Alison Weir's book of the same title, though academics felt that Fraser's work was the more impartial.

Fraser later published The Gunpowder Plot: Terror and Faith in 1605. Her acclaimed and in-depth biography of France's last legitimate queen, Marie Antoinette: The Journey, was adapted for film by Sofia Coppola, with the title role being played by Kirsten Dunst.

Fraser has also served as the editor for many monarchical biographies, including those featured in the Kings and Queens of England and Royal History of England series.