Whenever Ryan Bethencourt meets a promising start-up making an alternative to animal products, he knows who to call.

The "vegan mafia" is a group of powerful vegans across the country who fund start-ups, and try to wean people from their dependence on animal products.

"There's a whole community of us that are building and funding vegan companies," said Bethencourt, himself a longtime vegan, who runs a bio-tech accelerator called IndieBio.

The "vegan mafia" nickname is an informal nod to the so-called "PayPal mafia" — a group of powerful Silicon Valley investors and founders such as Peter Thiel, Elon Musk, and Reid Hoffman, who worked at the payments start-up in the 1990s.

The best-known start-ups in the space include Beyond Meat and Impossible Foods, which make plant-based meat-like and cheese-like products; and Pembient, which bioengineers wildlife products in a lab, like rhino horn and elephant ivory.

Some members of the vegan mafia are technology-focused venture capitalists such as Bill Maris, whom Bethencourt met at a vegan dinner, while others are former financiers or entrepreneurs who made their money elsewhere. (Maris confirmed that he's vegan, but declined to discuss his investments through a spokesperson.)

The network also includes:

Kyle Vogt, CEO of Cruise, a self-driving car technology acquired by General Motors for more than $1 billion;

Kevin Boylan, a former Wall Street trader who runs a fund for plant-centric companies called PowerPlant Ventures;

His business partner Mark Rampolla, founder of ZICO Coconut Water;

Jody Rasch, a former Moody's senior vice president managing a fund called VegInvest;

Seth Bannon, a social entrepreneur and founding partner at a seed fund called Fifty Years; and

Lisa Feria, CEO of Stray Dog Capital, a fund that also invests in early-stage companies.

CNBC interviewed half-a-dozen members of this mafia, who all stressed that they aren't solely investing in products intended for other vegans.

Instead, they are investing in products that appeal to the masses because they are healthier and cheaper.

One example of that is Geltor, which is designed to be less expensive than gelatin — which involves boiling the skin, tendons, bones from cows and pigs in a vat — as well as cruelty-free.

Or Boylan's portfolio company, an eatery chain called Veggie Grill, which primarily serves people who also eat meat.

Many of these investors said they were particularly impressed by the team behind Beyond Meat, which convinced major grocery chains like Whole Foods and Safeway to sell its plant-based burgers in the meat section. Beyond Meat also got an investment from meat processing giant Tyson Foods.