By Adam Jusko,,

We all know that professional athletes make a lot of money — millionaire athletes are commonplace, right? But being a billionaire? That’s a whole ‘nother level. (A billion is a thousand millions!)

Which athletes in the world of sports have reached billionaire status? For the most part we can only guess based on past earnings, though in at least one case we can be very sure. Here’s a list of athletes that have reached at least a billion in net worth or are very close:

1. Michael Jordan – Perhaps the greatest basketball player of all time, the vast majority of Jordan’s initial wealth actually came off the court from endorsements. What really pushed him over the top into billionaire status, though, is his majority ownership stake in the Charlotte Hornets. (He owns an estimated 90% of the team.) The Hornets are worth at least $1 billion, given recent sales of NBA teams, meaning that Jordan’s stake in the team might make him a billionaire even without any of his other money. Forbes estimates his net worth at $2.1 billion.

2. Tiger Woods – At one point, it seemed like a no-brainer to say that Tiger Woods was a billionaire, what with his many major golf tournament championships and his even more plentiful endorsements. But then he got divorced. And then he got hurt. So, some of those earnings are no longer in his pocket. Still, with a comeback of sorts over the last couple of years to add to his earlier pots of gold, he’s gotta be close, right? He’s the top lifetime earner on the PGA Tour, but that “only” accounts for a little over $100 million, so it’s really the many endorsement deals he’s had over his career that put him in the billionaire sphere. Woods has claimed he’s not a billionaire, but we think he’s just trying to look humble! Estimated net worth: $1 billion.

3. Floyd Mayweather – World’s richest boxer claims to be a billionaire, and he has earned at least $1 billion from his fights. Whether he has saved and invested enough of that money to be a billionaire in net worth is less obvious, because there is a hefty tax bite that comes out of those earnings, and he’s not known for making huge amounts of money from endorsements outside the ring. Our guess is that he’s still a bit under a billion — with a net worth of probably $850 million. (Still not too shabby.)

4. Roger Federer – While tennis might not seem like the easiest path to becoming a billionaire, there’s plenty of prize money and endorsements, and since it’s an individual sport, most of that money goes straight to that one athlete. The best tennis player over the past 20 years (and maybe ever) is Roger Federer, and he’s racked up the cash. Like others on this list, his endorsement deals are worth at least 5 times the amount he’s actually won through tournaments — and he’s won over $100 million from tournaments. Maybe not a billionaire yet, but most estimates have his net worth at around $750 million.

5. LeBron James – LeBron has made no secret of his desire to be a billionaire. He’s probably not there yet, but he’s made hundreds of millions from on-court salary and off-court endorsements. His move to Los Angeles and his entertainment company projects are likely fueling his wealth even faster. If he becomes an NBA owner one day (which is on his wish list), he’ll definitely hit that $1 billion eventually. Estimated net worth today: $600 million.

6. Phil Mickelson – With over 40 PGA Tour wins under his belt, and a raft of endorsements, Mickelson is just a shade under Tiger for the wealthiest golfer on the planet. He never quite had the star power of Woods, but he’s been a steady winner for over 25 years, giving him plenty of time to accumulate a huge nest egg. Estimated net worth: $500 million.

7. David Beckham – Famous footballer (soccer player) has made the majority of his fortune outside the “pitch,” with hundreds of millions of dollars in endorsements as a player and a smaller amount from modeling. He is also now an owner or part owner of two soccer teams as well. Beckham’s net worth is hard to pin down because his earnings are intertwined with those of his wife Victoria Beckham (Posh Spice of Spice Girls once upon a time), so saying what is his and what is hers is difficult to say. Between the two, they are close to being a billionaire couple, our guess on his net worth along: $500 million.

8. Cristiano Ronaldo – One of the best (if not THE best) footballers/soccer players of all time, Cristiano Ronaldo has parlayed his sporting success and good looks into a lucrative career built on both outrageous salaries and a marketing machine that has him marketing a wide variety of products. His fame is greater outside of the United States than inside, so his inclusion on this list may surprise some Americans, but football/soccer is the most popular sport worldwide, and Ronaldo has taken full advantage. Estimated net worth: $500 million.

9. Jack Nicklaus – Considered by many to be the greatest golfer ever, it’s obviously been a long time since Jack Nicklaus was making bank on the golf course. But the strength of his name has fueled a lot of very successful post-tour endeavors, in particular in golf course design, but also Jack Nicklaus apparel and equipment, endorsement deals and more. Jack Nicklaus’ estimated net worth is pegged at a bit under a half billion, say $450 million.

10. Shaquille O’Neal – A beast on the basketball court, Shaq has turned into a gentle giant pitchman in retirement, hawking any and every product under the sun. It’s worked out for him — his estimated net worth is $450 million.