Isabella of Bourbon-Parma (Spanish: Isabel María Luisa Antonieta, German: Isabella Maria Ludovica Antonia, French: Isabelle-Marie-Louise-Antoinette; 31 December 1741 – 27 November 1763) was a princess of Parma and infanta of Spain from the House of Bourbon-Parma as the daughter of Philip, Duke of Parma, and Louise-Élisabeth of France. She became an archduchess of Austria and crown princess of Bohemia and Hungary in 1760 by her marriage to Archduke Joseph of Austria, the future Joseph II, Holy Roman Emperor (she never became empress due to her early death).

Secretly an Enlightenment thinker, she was a prolific writer, and nineteen separate works by her have been preserved. She discussed philosophy, religion, ethics, politics, diplomacy, military theory, world trade, education and childrearing, human culture and societies, and the position of women. In secret essays, she argued for the intellectual equality of women. None of her writings were published in her life. Her Méditations chrétiennes ('Christian Meditations') were published in 1764, a year after her death. Some of her personal correspondence and other works have been published by biographers and historians.

Although her husband loved her, she did not fully return his feelings and found more fulfillment in her (likely romantic, possibly sexual) relationship with her sister-in-law, Archduchess Maria Christina. Despite her popularity at the Viennese court, she was unhappy because of the guilt of being unable to reciprocate her husband's feelings, compounded by the same-sex attraction that she considered sinful. A lonely childhood with demanding and unaffectionate caretakers, the sudden loss of her mother, a difficult birth and two miscarriages in the span of ten months, and later a fourth pregnancy all adversely affected her physical and mental health. She was described as melancholic and experienced suicidal ideation. Biographers have suggested that she suffered from depression or bipolar disorder, to which she was likely genetically predisposed. She died at the age of 21 from smallpox.

Infanta Isabel María Luisa Antonieta of Spain was born on 31 December 1741 at Buen Retiro Palace in Madrid as the first child of Infante Philip of Spain and his wife, Louise-Élisabeth of France (known as 'Madame Infante').

Isabella's parents were first cousins once removed with an age difference of six years (her mother had been twelve- and her father eighteen years old when they married). As the eldest daughter of Louis XV of France and the popular Queen Marie Leszczyńska, Madame Infante and her contemporaries thought that she should only marry a monarch or an heir apparent, yet the Infante Philip was only the third son of Philip V of Spain. Madame Infante was ambitious and strong-willed, unlike her husband. She soon took on a leading role in the marriage, working through her international connections to secure a higher position for themselves and more power for the Bourbons as a whole. She had a contentious relationship with her mother-in-law Elisabeth Farnese, the de facto ruler of Spain, whom she threatened in her influence over her son, but they worked together to advance Philip's career.

Madame Infante was fourteen years old when she gave birth to Isabella. The delivery was difficult and lasted for two days. Two months later, Philip left to fight in the War of the Austrian Succession, and he did not see his family again until his child was eight years old, although he kept up an intensive correspondence with his wife and mother, learning about Isabella from them. Her mother showed little affection towards Isabella and probably found the baby to be a burden.

For the first seven years of her life, Isabella was raised at the Madrid court of her paternal grandparents. Her grandmother, Queen Elisabeth, loved her, reporting regularly on her well-being, development, and behaviour to her absent son. Based on these letters, her mother never displayed warmth towards Isabella, and was impatient with her. When the child threw tantrums, she chastised her so severely that Queen Elisabeth called it a 'military drill'. Madame Infante reportedly found Isabella to be 'stubborn' and 'unbearable'. Isabella was raised by an aya (governess), the French-born widow Marie-Catherine de Bassecourt-Grigny, Marquise of Gonzalez (later suo jure marquise of Borghetto; 1693–1770). The Marquise retained a strong sense of etiquette and hierarchy from her previous position as dame d'honneur to Barbara of Portugal. Isabella developed a close bond with her aya, which inspired the jealousy of her mother.

Isabella's education was structured around contemporary ideals for princesses. The use of corporal punishment was ordered by her father and endorsed by her mother. According to her autobiography, she was an energetic and mischievous child, always loud, 'jumping, climbing, falling', breaking furniture and ornaments. Her favourite pastimes were chasing after butterflies, horse-riding, and performing stunts with a rope, but she also liked to write, sing, and draw. Because her behaviour was considered unsuitable for her position, her aya eventually forbade her access to ropes, horses, and swings. 'What to do in this sad situation? [...] But I eventually learned to be reasonable', Isabella commented as an adult. She started to entertain herself silently, later recalling that her 'head was always in the clouds, occupying itself with a hundred thousand ideas at once'. In 1746, when Isabella was four, a French envoy complimented her 'dignity', saying that she already knew 'who she is, to whom she belongs, and what she must be one day'. He also remarked on the coldness of Madame Infante towards Isabella. Growing up as an only child until the age of ten with no playmates and under strict control, her childhood has been characterised as 'lonely and austere' by Élisabeth Badinter.