UPDATED with quotes from Steven Spielberg, Kathleen Kennedy and Kundun producer: Melissa Mathison, the screenwriter behind what is arguably Steven Spielberg’s most beloved film, E.T. The Extra-Terrestrial, died today after a long illness. She was 65.

“Melissa had a heart that shined with generosity and love and burned as bright as the heart she gave E.T.,” Spielberg said in a statement.

Born in Los Angeles in 1950, Mathison broke into Hollywood E.T. Premierein 1979 with her script for The Black Stallion. But she would be best known for her next screenplay. The 1982 classic E.T. earned her an Academy Award nomination, and in later years Spielberg credited her heavily for the film’s success, saying on the DVD special edition: “It was a script I was willing to shoot the next day. It was so honest, and Melissa’s voice made a direct connection with my heart.” Mathison also served as assistance producer on the film, working under Kathleen Kennedy.

“Melissa was a remarkable friend not only to me but to everyone who had the privilege to know her,” said Kennedy. “She was fiercely intelligent, confident, soulful, strong and had a smile that would light up a room. I will miss her terribly.”

Mathison went on to pen the scripts for The Escape Artist (1982), the Spielberg-directed Kick The Can segment of Twilight Zone: The Movie (1983), Frank Oz’s adaptation of classic children’s book The Indian In The Cupboard (1995) and Martin Scorsese’s Kundun (1997). She also was a story consultant on the English-language translation of Hayao Miyazaki’s Ponyo.

“She was a lovely woman, and it’s a great loss,” Kundun producer Barbara De Fina told Deadline. “She was a wonderful writer. The project was about the Dalai Lama but at the core was about a boy separated from his home. I think of her as being a great parent. The choices that she made were so interesting and unusual, and it was all about family. When I think of what she’s written, it always comes back to family and home.”

The BFG 1Mathison also wrote Spielberg’s upcoming feature The BFG, her first screenplay in nearly two decades. Based on the Roald Dahl classic, it tells the story of a girl who encounters a fearsome-looking giant who turns out to be a kindhearted soul who is considered an outcast by the other giants because unlike his peers refuses to eat boys and girls. Disney will release the DreamWorks film July 1.

Mathison was married to Harrison Ford from 1983-2004, and the couple had two children, Malcolm Carswell Ford, and Georgia Ford. In later years, owing to her friendship with the Dalai Lama struck while she was writing Kundun, Mathison became an activist for Tibetan freedom and at the time of her death was a member of the board of the International Campaign for Tibet.