Donna O’Neill, 73; O.C. Philanthropist

Donna O’Neill, a conservationist and philanthropist who helped create one of Orange County’s most pristine land preserves and was a leader of the Hereditary Disease Foundation, has died. She was 73.

O’Neill, who had been diagnosed with cancer six months ago, died Thursday at the Ranch House on Rancho Mission Viejo.

She spent much of her life at the 23,850-acre ranch, which her husband’s family has owned since 1882.

It is the largest working cattle ranch in Orange County.

O’Neill was a driving force behind the family’s decision to set aside 1,250 acres of the ranch as a preserve for endangered species.

While serving as a board member of what became the Rancho Mission Viejo Land Conservancy, she promoted research on mountain lions, raptors and other indigenous creatures.

As a trustee of the Hereditary Disease Foundation, she and her husband, Richard, supported a unique approach to medical research. The foundation held workshops for scientists to brainstorm without worrying about the usual medical industry decorum or presenting formal papers.

Those familiar with the foundation say the workshops led to breakthroughs in genetic research.

O’Neill surrounded herself with writers and artists, and had been a benefactor to many of them.

“She knew and befriended them,” said Susan Spivak, a longtime friend.

“She hired Frank Gehry when he was not yet the Frank Gehry we know today. He designed the hay barn at the ranch and their swimming pool.

“She was the most extraordinary, unusual, elegant person I ever knew,” Spivak said. “She was someone I wished I could be more like.”

O’Neill is survived by her husband, Richard.

In lieu of flowers, contributions may be made to the Hereditary Disease Foundation, the Rancho Mission Viejo Land Conservancy and the National Audubon Society.