1. Alexandra Andresen - 21
Not only is this Norwegian heiress the world's youngest female billionaire, she's the world's youngest billionaire period.
Her family owns Ferd AS, but Andresen is best known as an equestrian champion and a model.
Still, with $1 billion in the bank already, maybe Andresen will take up the family business someday.
2. Marie Besnier Beauvalot - 28
Believe it or not, Beauvalot's fortune is built on milk money.
She and her siblings own Lactalis, the massive French dairy group.
The business has earned Beauvalot more than $5 billion.
3. Petra Stunt - 29
The daughter of Formula One owner Bernie Ecclestone, Stunt is a socialite, model and fashion designer.
She's married fellow billionaire James Stunt, but doesn't need to depend on him with $3 billion to her name.
4. Charlotte Casiraghi - 31
She models for Gucci and competes in equestrian contests, but Casiraghi is most famous for her royal blood.
She's the daughter of Caroline, Princess of Hanover, and the granddaughter of Grace Kelly and Prince Rainier.
With $5 billion in the bank, Casiraghi is ninth in line to the throne of Monacco.
5. Tamara Ecclestone Rutland - 33
Petra Stunt's older sister likes to play up her public persona as the princess of Formula One.
She's a TV presenter for an Italian sports network and starred in her own reality show.
Along with her inheritance, those projects have earned her $3 billion.
6. Athina Onassis - 33
Athina is the last surviving descendant of Aristotle Onassis, the Greek billionaire who famously married Jacqueline Kennedy.
That makes her Kennedy's granddaughter by marriage.
Soon it could be her only claim to fame - a divorce settlement and her wild spending are eating into Onassis's $1 billion nest egg.
7. Amanda Hearst - 34
The descendant of the famous newspaper mogul is a success story in her own right.
Hearst is a fashion model, and founded the charity Friends of Finn to care for mistreated pets.
Her family fortune is said to be worth $28 billion.
8. Lynsi Snyder - 35
Owning the fast food chain In-N-Out Burger has paid off for Snyder, netting her $1 billion.
But Snyder's life has also been tragic: her uncle died in a plane crash and she inherited In-N-Out after her father's drug overdose.
9. Georgina Bloomberg - 35
Georgina is the daughter of financial guru Michael Bloomberg, the 10th richest man on the planet.
She's made a name for herself as a professional equestrian competitor who also write young adult books about horse riding.
Those pursuits - and her father's money - mean she's worth a cool $11 billion.
10. Ivanka Trump - 36
While we know her best from her appearances on The Apprentice, Trump was also the executive vice president of her family's Trump Organization.
She and her husband - real estate tycoon Jared Kushner - are both advisers to her father, President Trump.
Their business holdings, including Ivanka's fashion line, make them worth $1 billion.
11. Holly Branson - 36
The daughter of Virgin's Sir Richard Branson may be even smarter than her famous dad.
She graduated with a degree in neurology, and worked in a hospital before joining her father's business.
Her share of the Virgin empire is reportedly worth $4 billion.
12. Dylan Lauren - 43
Lauren's father is the famous fashion designer Ralph Lauren, but she did not follow in his footsteps.
Her business is Dylan's Candy Bar in New York City - said to be the world's largest candy store.
Still, her shares in Ralph Lauren are worth $4 billion.
13. Jane Lauder - 44
Along with her sister Aerin, Jane is the heiress to the Estée Lauder brand.
She personally manages some of the conglomerates biggest brands, and her share of the company is worth $1 billion.
14. Anna Getty - 45
The heiress to the famous Getty family fortune, Anna is the granddaughter of the infamously cheap J. Paul Getty.
It must run in the family: the yoga instructor and cookbook writer reportedly renounced her U.S. citizenship to avoid paying taxes on her $2 billion fortune.
15. Samantha Kluge - 47
Samantha's father was TV mogul John Kluge, who was once the wealthiest man in America.
While Kluge had a reputation as a party girl in her youth, today she's focused on looking after her son - and her $2 billion inheritance.
16. Sara Blakely - 47
Blakely took a simple idea - a comfortable and flattering alternative to pantyhose - and turned it into the massive Spanx empire.
Her trendy underwear line has earned Blakely $1 billion, and put her on Time's lists of most powerful and influential women.
17. Aerin Lauder - 47
Jane Lauder's older sister is even more invested in the Estée Lauder brand.
Her Aerin product line includes fashion, perfumes, cosmetics, and furniture.
Lauder's $2 billion fortune says she must know what her customers like.
18. Sheryl Sandberg - 48
After leaving her executive position at Google, Sandberg became a board member and the Chief Operating Officer of Facebook.
Her role at the social media giant means she's worth $1 billion.
19. Laurene Powell Jobs - 54
Most of Powell's $19 billion fortune is from her late husband, Apple co-founder Steve Jobs.
She puts her fortune to good use, investing it in educational charities and wildlife conservation.
20. Meg Whitman - 61
Name a major America company and Whitman has probably worked for it or dealt with it.
Her impressive resume includes time as the president and CEO of Hewlett Packard, along with executive positions at Procter & Gamble, Hasbro, and eBay.
She's set her sights on becoming California's governor, and could pull it off thanks to her $1 billion net worth.
21. Christy Walton - 69
Walton married one of the heirs to the Walmart fortune, and was believed to be the richest woman in America for almost a decade.
In fact, most of her late husband's money went to their son, Lukas, but Walton still has $5 billion.
Were you surprised by how much money some of these women made?