Elisabeth Brooke (25 June 1526 – 2 April 1565) was the eldest daughter of George Brooke, 9th Baron Cobham of Kent and Anne, his wife. She was the niece of Sir Thomas Wyatt the elder, the courtier-poet credited with bringing the sonnet form into the English language, and Elizabeth Brooke who was associated with Henry VIII of England. Elisabeth openly lived in adultery with William Parr, 1st Marquess of Northampton and bigamously married him. At times, she was accepted at court as the Marchioness of Northampton. She was the sister-in-law of Catherine Parr, King Henry VIII's sixth queen. Her first cousin, Thomas Wyatt the Younger, was the leader of a rebellion against Queen Mary I known as Wyatt's Rebellion. The whole family was implicated. She became one of the most influential courtiers again during the reign of Elizabeth I.
Elisabeth was described as vivacious, kind and one of the most beautiful women at court. Her relationship with William Parr, Catherine Parr’s brother, would shape the politics of England for many years to come. Elisabeth became a queenmaker when she arranged for Lady Jane Grey to inherit the crown of England, in accordance with Henry VIII’s earlier wishes, as shown in his will. As the Marchioness of Northampton, Elisabeth performed much of a queen’s role during the reign of Edward VI, as she was the wife of the second most important man at court.
Elisabeth Brooke was around fourteen years old when she arrived at court as a maid-of-honour to Queen Catherine Howard. Her aunt and namesake, Elizabeth Brooke, was notorious as her husband, Sir Thomas Wyatt, had left her after he discovered her adultery. The day after Catherine Howard was condemned to death for adultery, the Imperial ambassador wrote that Henry was paying particular attention to the elder Elizabeth Brooke, and that 'she had wit enough to do as badly as the others if she wished.' She was thought to be a possible candidate for wife number six. Elisabeth’s father was George Brooke, 9th Baron Cobham of Kent.