Olivia Trinidad Harrison (née Arias; born May 18, 1948) is an American author and film producer, and the widow of English musician George Harrison of the Beatles. She first worked in the music industry in Los Angeles, for A&M Records, where she met Harrison and then helped run his Dark Horse record label. In 1990, she launched the Romanian Angel Appeal to raise funds for the thousands of orphans left abandoned in Romania after the fall of Communism.

Since her husband's death in 2001, Olivia has continued George’s international aid efforts through projects in partnership with UNICEF, and is the curator of film, book and music releases related to his legacy. She represents his voice on the Beatles' Apple Corps board and is similarly a director of his charity organisation, the Material World Foundation (MWF). Under the auspices of MWF, she has sponsored the preservation of film history in collaboration with American director Martin Scorsese. These restoration projects include short films by Charlie Chaplin and works from 1940s Mexican cinema.

She and her husband shared an interest in Eastern mysticism and spiritual practice, and her presence in his life, starting in the mid-1970s, began a period of more optimistic content in Harrison's music. At their Friar Park home in December 1999, when she overpowered a knife-wielding intruder who had repeatedly stabbed George, she was recognized as having saved her husband's life. Among Harrison's film projects, her production of Concert for George won the Grammy Award for Best Long Form Music Video in 2005, and her co-production of Scorsese's 2011 documentary George Harrison: Living in the Material World won an Emmy Award in the category "Outstanding Documentary or Nonfiction Special". She authored books to accompany both these films, and in 2017 compiled a revised edition of George's 1980 autobiography, I, Me, Mine. Her son with George, Dhani Harrison, is also a musician.

Arias was born in Los Angeles. Her grandparents migrated to California, having grown up in Guanajuato in central Mexico. Her father, Zeke, was a dry cleaner, and her mother, Mary Louise, worked as a seamstress. Arias's siblings include Peter and Louise. Spending her early childhood in Los Angeles, she grew up with a Mexican, Spanish-speaking entourage. In a 2016 interview, she recalled that Mexican music and films were a regular part of her upbringing, with Zeke having been a singer and guitarist, and that Jorge Negrete, Trío Calaveras and Trío Los Panchos were among the artists she enjoyed. Later in her youth her family moved west to Hawthorne where she attended Hawthorne High School in the 1960s.

In 1972, she began working for A&M Records, at the former site of Charlie Chaplin Studios in Hollywood. By 1974, as a member of the marketing department, she regularly liaised by long-distance telephone with George Harrison, whose new record label, Dark Horse, was distributed by A&M. Impressed with Arias, Harrison arranged for her to work exclusively for Dark Horse Records. The pair met for the first time in October 1974 and soon became romantically involved. Until the late 1970s, Arias worked with a roster of artists that included Ravi Shankar, Splinter, Stairsteps, Attitudes, Keni Burke and Henry McCullough. According to author Robert Rodriguez, she was "a capable and even-tempered administrator, ably handling the routine chaos involved with setting up a record label and dealing with all manner of personalities".

Before meeting Harrison, Arias had studied meditation with the Indian guru Maharaj-ji. Their shared interest in spirituality, together with a lifestyle incorporating vegetarianism, had a calming effect on Harrison, whose reliance on alcohol and other drugs Arias helped curb. His 1976 album Thirty Three & 1/3 conveyed a more contented outlook in which he expressed his faith without the disapproving tone that, for many music critics, had marred his previous two albums. While accompanying Harrison on his promotional campaign for Thirty Three & 1/3, Arias told an interviewer: "We have a nice relationship. When you strive for something higher in the next world, you have a much easier time in this one."

Arias gave birth to the couple's son Dhani Harrison at Princess Christian Nursing Home on 1 August 1978. The following month, Olivia and George married in a private ceremony at the Henley-on-Thames Register Office in England. Their contentment during this period was again reflected in George's music, much of which he wrote at their holiday property on Maui in Hawaii. His self-titled 1979 album includes the song "Dark Sweet Lady," which he said best captured the renewal Arias had provided in his life.

She was also habitually present in the recording studio with her husband. Producer Giles Martin said that she was often the one operating the recording button.