The actress Elizabeth Hurley traveled to Nairobi from London a few weeks ago to witness the Kenyan government burn 105 tons of poached ivory, saying she “felt sickened to watch the great pyres.”

Lupita Nyong’o, the Oscar-winning actress, posed with a baby elephant rescued from a poacher’s snare, telling her 2.6 million Instagram followers: “33,000 elephants are killed every year so that a few people can wear and display a few trinkets. We can do better.”

Susan Sarandon raised thousands for an elephant benefit in London last year. “The crisis facing elephants is particularly tragic,” she said recently.

“Everything about them is extraordinary,” she said. “Their intelligence and emotional complexity, the depth of their matriarchal social ties and just their sheer physical majesty.”

These days, it seems, for every elephant that falls to poachers, a celebrity rises to join the fight to save them.

#SaveTheElephants has become a rallying cry among the celebrity class, a made-for-Hollywood issue that features a beloved victim, menacing villains (gangsters, warlords) and undeniable drama (if current poaching rates continue, wild elephant populations could vanish in some African countries, conservationists say).

No wonder elephant conservation, like the rain forest in the ’90s, has become an issue that celebrities can rally behind, uniting stars of the big screen (Arnold Schwarzenegger, Edward Norton) and small (Ian Somerhalder of “The Vampire Diaries”), not to mention sports stars (Yao Ming, Andy Murray), fashion designers (Tommy Hilfiger, Diane von Furstenberg) and royals (the Duke and Duchess of Cambridge, Prince William and Kate Middleton).

The cause célèbre, in other words, has become a cause celeb.

“Stars are magnets, and they attract other stars,” said Laura Fredricks, a philanthropy consultant and lecturer at New York University. “And before you know it, the whole celebrity scene is totally on board with saving elephants around the world. It’s the sexy cause of the moment.”

There is no denying that the stakes are high. As of 2013, the elephant population in Africa had plummeted to about 400,000, according to the conservation site elephantdatabase.org, from some 1.3 million in 1979, due to strong demand for ivory, particularly in Asia, where it is a status symbol for the burgeoning middle class.

(The United States remains a leading market. Despite a longstanding ban on commercial importation, allowances for legal ivory — say, in antiques — create loopholes for ivory from poached elephants to enter the market, activists say.)

The poaching crisis has come to resemble a war. With ivory fetching more than $1,000 a pound, according to the conservation group Save the Elephants, poachers (often employed by criminal syndicates and sometimes armed with helicopters, night-vision goggles and automatic weapons) are slaughtering tens of thousands of elephants a year, threatening to send the world’s largest land mammal the way of its forebear, the woolly mammoth.

“What I’m seeing now is a lot of anger,” said Andrew Harmon, a spokesman for WildAid, a global conservation group based in San Francisco. “People are just really afraid that this will be a generation that will see elephants go extinct in the wild.”

Given the climate, conservationists have embraced celebrities amplification of their message, said Misty Herrin, a spokeswoman for the Nature Conservancy.

Indeed, a photo that Leonardo DiCaprio posted on Instagram two months ago showing him posing with two endangered Sumatran elephants in Indonesia got nearly 500,000 likes. (In 2013, Mr. DiCaprio led a drive to deliver 1.6 million signatures to the prime minister of Thailand in support of a proposed ban on the ivory trade, a World Wildlife Fund spokesman said.)

Last November, the Wildlife Conservation Society cast Mr. Schwarzenegger to star in a promotional video for its 96 Elephants campaign. Acting Terminator-tough and posing in front of an Army tank, the human action figure barked, “Hey, stop killing 96 elephants every day just because of this ivory,” before blowing up an elephant tusk with explosives.

The video generated 1.4 million views across various channels and more than 80,000 letters to support legislative action, a group spokeswoman said.

Similarly, Mr. Norton appeared in a chilling 2014 public service announcement for WildAid, in partnership with Save the Elephants and the African Wildlife Foundation, titled “Party,” which cuts between a cocktail party filled with ivory objects and sneering traffickers, and footage of elephants being cut down by bullets.

“If you buy elephant ivory, you may be part of a criminal gang, ” the actor says in the video. “And because you’re paying them, that makes you the boss.”

Social media has played a huge role in publicizing the issue, with more than 100,000 users following the lead of Ms. Nyong’o, Yoko Ono and other celebrities who signed onto WildAid’s #JoinTheHerd campaign. In the spirit of Facebook’s popular rainbow filter to show support for same-sex marriage, users can upload split-screen photos of their faces with an elephant face as their profile photo.

To combat demand for ivory in Asia, the group has also enlisted the likes of Yao Ming (the Chinese-born former Houston Rockets star), Li Bingbing (a prominent actress in China) and Maggie Q (whose mother is Vietnamese actress who starred in the CW assassin drama “Nikita” and CBS’s “Stalker”).

“It basically takes an army of 30 people to protect one elephant,” said Maggie Q, who began her acting career in Asia. “On the other hand, what is most effective is to speak to consumers. And there’s an entire side of the world that knows me, knows my values and knows my face.”

Many celebrities go beyond supplying a pretty picture and a quote.

Last summer, Jared Leto, an ambassador for the World Wildlife Fund, co-wrote an editorial in Time magazine demanding that the United States do more to stop the slaughter. “Our collective efforts don’t match the scale and speed of the calamity before us,” he said.

A number of Hollywood notables have also trained their cameras on the cause, making documentaries about the plight of the elephants: Kathryn Bigelow, the Oscar-winning director (the short film “Last Days”); Kristin Davis of “Sex and the City” (who produced and self-financed “Gardeners of Eden”); and Paul Allen, the Microsoft co-founder and Hollywood producer. (He produced “Naledi: A Baby Elephant’s Tale,” which will debut next month at the Seattle International Film Festival.)

The celebrity efforts provide another crucial weapon for conservationists: money.

While philanthropic associations do not track donations to elephant causes specifically, fund-raising for wildlife in general (including other much-publicized endangered animals like rhinos and tigers), appears to be on the rise, according to the Giving USA Foundation.

In 2014, donations to animal and environmental causes rose to $10.5 billion, up 43 percent since 2009.

At a grass-roots level, a celebrity-fueled social media campaign like #JointheHerd can persuade the masses to reach for the credit card, said Mr. Harmon of WildAid. Since the campaign began in February, WildAid has seen the number of small donors to its elephant initiative rise 94 percent, he said.

Celebrities also persuade other celebrities to open their wallets.

Last fall, for example, Owen Wilson hosted the Elephants Forever Auction at Sotheby’s, featuring artwork by Tom Sachs and Rob Pruitt, among others, that drew the likes of Waris Ahluwalia, the actor and jewelry designer, and Ms. Sarandon and raised more than $1 million for Elephant Family, benefiting Asian elephants, and Space for Giants.

“Maybe it sounds corny, but there’s sort of a wisdom to elephants,” InStyle quoted Mr. Wilson as saying.

Elephant Family will make further inroads into the art world this summer, when it takes the Elephant Parade, a showcase of elephant-themed outdoor art by David Yarrow, David LaChapelle, and other artists, to the Hamptons

Similarly, the fashion industry has gotten involved. Two years ago during MADE Fashion Week the Clinton Foundation headed a campaign to install a 10-foot pink elephant, designed by the artist Tristin Lowe, at Milk Studios to raise awareness for its #SaveElephants campaign. (The concept reportedly grew out of conversations among Chelsea Clinton, Diane Von Furstenberg and Oscar de la Renta, all elephant champions).

At Vancouver Fashion Week in February, a group called Elephanatics enlisted 13 designers to conjure elephant-inspired couture clothing “to reach out to a crowd that is more or less responsible for the plight of elephants — people in fashion,” said Ava J. Holmes, who produced the show. J. Crew has been selling a “Save the Elephants” T-shirt for charity, featuring an illustration by the artist Hugo Guinness.

Certainly, it will take more than art auctions and fashion shows to overcome this global crisis. Like the drug trade, the illicit ivory trade involves vast criminal syndicates and countless corrupt government officials, said Trevor Neilson, the president of Global Philanthropy Group in Los Angeles.

“If you want to understand the issue, you have to talk former C.I.A. officers who are in touch with Kenyan intelligence who can tell you who is corrupt at the port at Mombasa,” Mr. Neilson said.

By contrast, “When a well-meaning reality TV star in Los Angeles is tweeting ‘save the elephants,’ I think it’s safe to say that that has no impact whatsoever,” he said.

Even so, there are reasons for hope, conservationists say. On a visit to the United States in September, President Xi Jinping of China promised to enact “nearly complete” bans on ivory import and export.

In the United States, four states including California and New York have enacted ivory restrictions, with others pending. (Citing “horrific cruelty,” Meryl Streep joined the Humane Society’s fight in her home state of New Jersey. Woody Harrelson told representatives in Hawaii that “the world is watching.”)

President Obama has called for a near-total ban on the ivory trade in the United States, and conservation groups expect the new law to be put in effect this summer.

Meanwhile, in a related issue, Ringling Bros. and Barnum & Bailey agreed to retire its touring circus elephants this month, after years of strident opposition from stars like Alec Baldwin, working with People for the Ethical Treatment of Animals.

Such progress is enough to keep celebrities like Ms. Davis going. And going. And going. In recent years, the erstwhile Charlotte has made elephants a mission, taking some 15 trips to Africa, helping serve the David Sheldrick Wildlife Trust, which rescues baby elephants orphaned by poaching, and releasing the unflinching documentary “Gardeners of Eden” in 2014.

She finds the issue gripping in part because elephants seem so human in their behavior, she said: Each herd has its matriarchs, its wise old aunts, its rowdy teenagers. When an elephant dies, the others mourn. “They touch the body with their feet, smell it with their trunks, and stand around for a day or longer,” Ms. Davis said. “It’s almost like sitting shiva.”

And unfortunately, there is a lot of that going on in Africa these days, she said. “How on earth will we be able turn to our children and say, ‘All those elephants in books, they used to be everywhere, now they’re gone.’”