Rachel Mary Berkeley Portman (born 11 December 1960) is a British composer. She was the first female composer to win the Academy Award for Best Original Score (for Emma), and was nominated two further times (for The Cider House Rules and Chocolat). She has composed more than one hundred scores for film, television and theatre, and has collaborated with the BBC on several projects, including an opera based on The Little Prince and a choral symphony called The Water Diviner.

Portman's career in music began with writing music for drama in BBC and Channel 4 films such as Oranges Are Not the Only Fruit, Mike Leigh's Four Days in July and Jim Henson's Storyteller series.

Her success in her profession derives from "a natural affinity for the particularities of a film's narrative" and "her ability to forge a comprehensive articulation of a film's emotional thesis via her gift for colour and storytelling. Her acute career choices complement her compositional gifts, and she has carved out a unique niche as a composer of human-size stories, an increasing rarity in the box office-dominated film world of the 2000s and 2010s."

She was appointed an Officer of the Order of the British Empire in 2010, and is an honorary member of Worcester College, Oxford. Portman is a Fellow of the Royal College of Music. She was made an honorary fellow in a ceremony at the RCM, where Prince Charles (now King Charles III), then President of the RCM, presented the award.

Portman was born in Haslemere in Surrey, England, the daughter of Sheila Margaret Penelope (née Mowat) Portman and Berkeley Charles Berkeley Portman. She was educated at Charterhouse and became interested in music from a young age, beginning composing at the age of 14. Portman studied Music at Worcester College, Oxford, and composition with Roger Steptoe. It was here that her interest in composing music for films began, as she started experimenting with writing music for student films and theatre productions. She composed for Oxford Playhouse productions and made the soundtrack for a student film, Privileged, which was sold to the BBC.

Her first professional score was commissioned by David Puttnam, and was the soundtrack for the 1982 film Experience Preferred... But Not Essential. Later, she started to compose music for BBC and Channel 4 shows and movies, such as Oranges Are Not The Only Fruit, Four Days in July by Mike Leigh and The Storyteller by Jim Henson.

Since 1992 Rachel Portman has been in demand for Hollywood productions, and remains one of the few female composers to have achieved significant success at this level. In an interview, discussing the influence of her success to inspire women composers, she states: "I really haven’t ever thought of myself as a female composer, but rather as a composer. It never occurred to me I was one of the only women composers in film when I started out. There is still a huge imbalance in the industry when there are many, many greatly talented women composers of film music around now. I hope it becomes more and more the norm to see women credited as composers in film and TV in the future."

Portman has also written several concert and stage commissions including a musical of Little House on the Prairie. In 2003 her opera The Little Prince premiered at the Houston Grand Opera and has since been performed throughout the United States and recorded under the auspices of the BBC. Based on Antoine de Saint-Exupéry's novel of the same name, Portman's The Little Prince is one of relatively few operas intended for both children and adults. Characterized by cleanly etched vocal lines for boy soprano and lively children's choruses, the opera represents the composer's most ambitious work. She also premiered The Water Diviner's Tale (2007), a choral symphony inspired in climate change for the BBC Proms, and later, Endangered (2012), an orchestral piece commissioned by the National Centre for the Performing Arts (China) in Beijing for a concert on the occasion of the World Environment Day in 2013.