Victoria Sant, a force in Washington philanthropy whose multi­million-dollar beneficence supported causes as diverse as art galleries, women’s empowerment, efforts to curb teenage pregnancy, and the National Zoo’s giant-panda project, died Dec. 11 at her home in Washington. She was 79.

The cause was cancer, said a son, Alexis “Lex” Sant.

A native Californian with an interest in conservation and global population issues, Mrs. Sant settled in Washington in 1974 when her husband, Roger, was appointed to a position at the Federal Energy Administration. He later co-founded Applied Energy Services (AES), a Fortune 200 global energy producer that made him a billionaire after the company went public in 1991 and became the source of the family’s sprawling philanthropic efforts.

Mrs. Sant was the first nonfamily chairwoman of the Phillips Collection art museum and from 2000 to 2015 was a trustee of the National Gallery of Art, including 12 years as board chairwoman. With her husband, she gave $26.5 million to the National Gallery. She also was an art collector and donor of art to both museums, including “Multiverse,” the light installation in the tunnel connecting the National Gallery’s East and West wings.

Her money helped endow the positions of music director of the National Symphony Orchestra and director of the National Museum of Natural History. She gave $800,000 to the National Zoo to support the giant pandas. In 2008, she gave $25 million for Sant Ocean Hall at the natural history museum.

She was national board chairwoman of Population Action International, a charitable nongovernmental organization advocating family planning and reproductive health care.

“Washington is full of rich folks who care about issues and back them up with big checks,” The Washington Post noted in 2002 in a rare profile of the publicity-averse Mrs. Sant. “But Vicki Sant is, according to those who work with her, the gold standard. . . . She gives money, raises money, leverages resources, sees the big picture and doesn’t throw her weight around.”

Earl A. “Rusty” Powell III, then the director of the National Gallery of Art, told the newspaper, “If you were trying to clone the perfect trustee, she’s the model for it.”

Victoria Valerie Post was born in Santa Cruz, Calif., on July 19, 1939. Her father at age 5 had fled the turmoil of pre-revolutionary Russia with his family, settling in San Francisco shortly after the 1906 earthquake. He became an engineer and later a business entrepreneur. Her mother, a native Californian, was a registered nurse.

Her parents lived on a ranch in the nearby hills of Soquel, and she grew up exploring the countryside with her siblings. She graduated in 1961 from Stanford University, where she also did a year of postgraduate study in speech pa­thol­ogy before marrying Norman Rosenberg and moving to New York. The marriage was annulled after 18 months and, in 1966, she returned to California and worked as a sales manager at San Francisco hotels.

(She later served on the Stanford Board of Trustees and was a major supporter of the Stanford-in-Washington program that brings students to the District to work as interns in government.)

She married Roger Sant in 1968. In addition to her husband, of Washington, survivors include their twin children, Alison Sant-Johnson of San Francisco and Lex Sant of Washington; two stepchildren, Shari Sant Plummer of Malibu, Calif., and Michael Sant of Los Angeles; two brothers; a half-sister; two stepsisters; and six grandchildren.

Roger Sant helped start AES in 1981 and, a decade later, the Sants established a private family foundation called the Summit Foundation, whose first two grants were to the Children’s Defense Fund and the Nature Conservancy. Later grants were targeted to clean up the Anacostia River and conserve the Mesoamerican Barrier Reef System.

Mrs. Sant tended to be the public point person of the Sant philanthropy, but she and her husband said the work was a joint effort. Their philanthropy and bipartisan friendships put them on the top of Washington’s A-list for decades, although she always preferred to stay out of the spotlight.

“There are different reasons to why people put their names on things or why people give,” she told The Post in 2002. “People give because someone asks them who they can’t say no to, they give because they would like recognition — which is also totally valid — they give because they really care about the project. . . . I don’t mind my name being used, I don’t mind my picture being used, I don’t mind any of that if it forwards the work. But if it’s to forward me, then I’m not as interested.”