A man in a business suit lifts a barbell in a gym.

Image source: Getty Images.

It's no secret that pro athletes can make millions on the playing field or in the arena, but some sports stars keep hustling long after their playing days are over. With a combination of money from their sports careers, the fame that comes with being an elite athlete, and the hard work and smarts that go into any successful business venture, athletes sometimes go on to make fortunes in industries outside of sports.

Here are a few former sports stars who have defied the trope of the bankrupt retired athlete.

Tim Horton fights for the puck against an opponent.

Image source: Tim Horton's.

1. Tim Horton

You may only know Tim Horton's for its coffee and donuts, but Canadians are well aware their national fast-food chain is named for hockey star Tim Horton. Horton played in the National Hockey League for 24 years, the vast majority of which he spent with the Toronto Maple Leafs. His life came to a tragic end in 1974 when he was killed in a car accident. He was 44 at the time but still playing with the Buffalo Sabres.

Horton co-founded the coffee chain bearing his name in 1964, putting some of his own inventions on the menu, and the chain became a multimillion-dollar franchise in 1968. After Horton's untimely death, his business partner Ron Joyce bought out his shares from his family for $1 million. At the time the chain had 40 stores; today it has grown to more than 4,000 locations around the world, and it's one of three global chains, along with Burger King and Popeye's, that make up Restaurant Brands International (NYSE:QSR) a fast-food conglomerate that has a market cap of $30 billion today.

Magic Johnson Sports store in Los Angeles International Airport

Magic Johnson Sports store in Los Angeles International Airport. Image source: Magic Johnson Enterprises.

2. Magic Johnson

Magic Johnson may be best-known for his on-court wizardry and no-look passes while he led the "Showtime" Los Angeles Lakers of the 1980s, but the basketball legend has had an enviable second act in business. As the head of Magic Johnson Enterprises, Johnson oversees a company worth more than $1 billion. He started with a movie theater chain and then became a Starbucks franchisee with 125 stores before selling that business. Today, MJE has controlling stakes in Equitrust, a financial services company; ASPiRE, an African-American TV network; and SodexoMAGIC, a food services provider.

Johnson is also a co-owner of the LA Dodgers, LA Sparks, and LA Galaxy.

pair of boxing gloves hanging from the rope of a boxing ring

Image source: Getty Images.

3. Floyd Mayweather

Floyd Mayweather may not have made his money outside of sports, but he deserves a mention here, as his financial success comes more from his business acumen than from his fast fists. Mayweather broke the traditional boxing model when he didn't hire an outside promoter, instead starting his own promotion company nicknamed "The Money Team." He even nicknamed himself "Money."

As a result, Mayweather reaps all of the financial rewards of his fights -- and with his knack for promotion and his skills in the ring, those rewards have been ample. Mayweather made an estimated $300 million from his August fight with Conor McGregor, including pay-per-view and gate receipts, and the boxing champ has an estimated net worth of $450 million.

two pro wrestlers in wrestling ring

Image source: Getty Images.

4. Dwayne Johnson 

Dwayne "The Rock" Johnson may have the most impressive record of success of any famous athlete. Johnson played football at the University of Miami, where his team won the 1991 national championship, and he briefly played for the Calgary Stampeders of the Canadian Football League. After his football career ended, Johnson rose to fame in World Wrestling Entertainment under the name "The Rock," and he parlayed that into a Hollywood career with early roles in the Fast and the Furious franchise.

Today, Johnson is one of the highest-paid actors in Hollywood, and he owns Seven Bucks Productions with his business partner Dany Garcia.

American football sitting on football field

Image source: Getty Images.

5. John Elway  

Idolized in Colorado for leading the Broncos to two Super Bowl victories, Elway continued to make millions long after his football career ended. Even while he was quarterback, Elway owned a string of car dealerships that he sold to AutoNation in 1997 for $82.5 million. Today, the Hall-of-Famer once again owns several dealerships as well two steakhouses, and he was a co-owner of the Arena Football team Colorado Crush until the league suspended operations in 2009.

He has also returned to his roots with the Broncos, serving as the executive vice president of football operations, which puts him in charge of all football-related decisions.

side shot of man holding basketball in one hand

Image source: Getty Images.

6. Shaquille O'Neal

Best known for his monster dunks and 1,000-watt smile, NBA Hall-of-Famer Shaq has made many investments across of a variety of businesses. Shaq invested in Alphabet (formerly known as Google) stock before its IPO. He has owned full or partial stakes in 17 Auntie Anne's pretzel shops, 155 Five Guys restaurants, 150 car washes, 40 24-hour fitness centers, some Vegas nightclubs, Muscle Milk (which was acquired by Hormel for $450 million), and Vitaminwater (which was bought by Coca-Cola for $4.1 billion).

Today, Shaq is worth an estimated $350 million.

American football player in number 27 jersey running with the ball

Image source: Getty Images.

7. Eddie George

This Heisman trophy winner and longtime Tennessee Titans running back is a veritable renaissance man. Since retiring from the NFL, George has launched a wealth management company, opened a restaurant called Eddie George's Grille 27, and started a landscape architecture firm, EDGE.

George has also earned an MBA from Northwestern University and even performed on Broadway, starring in Chicago as Billy Flynn. With George's far-reaching ambitions, more new enterprises could be on the way.

Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Jeremy Bowman owns shares of Starbucks. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), and Starbucks. The Motley Fool has a disclosure policy.