This post is compliments of  OnlineMBA.com.

For many who reach the top echelons of business, retirement is a time to enjoy the spoils of a life well lived and years of hard work and perseverance. Others, however, take a different approach. For every businessman anticipating retirement, there’s also one who dreams of working until old age, and more than a few that make that a reality. Some don’t want to leave a company they’ve helped to build or say goodbye to the work they find so fulfilling, even if it means more time for family and relaxation.

Here, we’ve listed just a handful of the top execs, business leaders, and entrepreneurial geniuses who don’t want to leave the working world for retirement, despite having more than enough money to relax lavishly. These workaholics are keeping busy with work well into their 70s, 80s, and yes, even 90s, proving that age really is just a number.

1. Peter Cooper

   
   Peter Cooper is one of the best-known early American businessmen, working throughout his life in a variety of careers ranging from mechanic to teacher. He is most famous, however, for his work as industrialist, designing and building America’s first steam locomotive in 1830. Cooper would later run a successful iron mill and make some very savvy investments in real estate and the telegraph that would make him an even richer man. Cooper loved his work so much, he never truly retired, exchanging his career in business for one in politics, and eventually founding a college. Cooper died in 1883 at the age of 92.

2. Wallace Stevens

   
   Wallace Stevens is perhaps best known for his Modernist poetry, but many may not realize that he was also a lawyer and businessman who worked for Hartford Insurance. Stevens considered himself a poet, but he never retired from the insurance company, working there until his 1955 death at the age of 76.

3. Jack Mullowney

   
   Jack Mullowney had a pretty eventful life as a businessman. He published the Times-News in the 1960s, came up with the advertising campaign for the Jolly Green Giant, helped establish the College of Southern Idaho, and worked as a successful commodities trader. Mullowney was good at business and enjoyed being active, never retiring from his trading or public service work. He worked right up until his death at age 91 in 2010.

4. Warren Buffett

   
   Few names on this list are as well-known as that of iconic business and investment mogul Warren Buffett, especially with his recent pleas for higher taxes on the wealthy. Buffett began his career in finance in the early 1950s after graduating from Columbia Business School, going on to earn an estimated $62 billion dollars over his career. Despite being one of the world’s richest men, Buffett has no plans for retirement in the immediate future. While he has scaled back his other commitments, Buffett is still primary shareholder, chairman, and CEO of Berkshire Hathaway, and at 81 years of age shows no signs of slowing down.

5. Al Davis

   
   Al Davis was a high profile football coach for the Chargers and later the Raiders, eventually going on to be the primary owner and CEO of the Oakland-based team. Davis made quite a name for himself on the business side of football, and under his management (and with the help of legendary coach John Madden) the team would numerous championships, titles, and three Super Bowls. Despite making it into the Football Hall of Fame, Davis had no plans to retire, announcing in 2007 that he would not leave his position until the team wins two more Super Bowls or he died. Unfortunately for Davis, his death came first, and he passed away in October of 2011 at age 82.

6. Richard DeVos

   
   You may wince when you hear the word Amway, but DeVos sure doesn’t. The company he started with high school friend Jay Van Andel in 1959 has netted him over $4.4 billion in sales over his lifetime. DeVos isn’t working with Amway any longer since he stepped down in 1993, but that doesn’t mean he’s retired. He now spends his time focusing on owning and managing the Orlando Magic and ran for governor of Michigan in 2006. Not bad for 85!

7. J.W. Marriott Jr.

   
   Bill Marriott, as he is most often called, is the son of the founder of the Marriott hotel chain. While his dad set the stage for success, Bill led the company into the international market, allowing them to maintain over 3,200 (and growing) properties worldwide. Marriott has been President and CEO of the company since 1993, and despite pushing 80, he isn’t planning to retire from the family business anytime soon. In fact, he even still maintains a blog.

8. David Murdock

   
   This 88-year-old businessman is one of the wealthiest men in the world, but that hasn’t pushed him to sit back and enjoy a lengthy retirement. Murdock turned the nearly bankrupt Dole Food Company into profitable business after his purchase of its managing firm Castle & Cooke in 1985 (acquiring the entire Hawaiian island of Lana’i in the process). Today, the company is worth over $446 million and he is still the Chairman and CEO of the company. Of course, like many on this list, Murdock isn’t just a businessman. After the death of his wife from cancer at only 42, Murdock became passionate about cancer research, and in 2006 opened the California Health and Longevity Institute.

9. Albert Frere

   
   Frere might not be a household name in America, but this Belgian businessman is quite a powerhouse across the Atlantic. Frere is the richest man in Belgium, building a $3.5 billion dollar fortune through his work as chairman and director of Groupe Bruxelles Lambert. While you might be tempted to think he’s slowing down or playing it safe as he ages, his actions prove otherwise. In 2008, he brokered a huge deal with Gaz de France and keeps busy playing sports and drinking wine from the winery he owns with mega-rich businessman Bernard Arnault. This baron (literally) has no plans for retirement, even as he nears his 86th birthday.

10. Carl Icahn

    
    Ichan is famous for swooping in and taking over businesses, from Time Warner to Yahoo! His nine billion dollar fortune was accumulated through years of careful investing through numerous holding companies and with executive positions at Nabisco, Texaco, Motorola and Marvel, he’s a business legend to be reckoned with. The 75-year-old Ichan may be past retirement age, but he’s still working hard, taking on the role of director at Yahoo! in 2008 (he has since resigned) and planning a number of buyouts, investments, and takeovers (though not all successful) of big companies like Clorox, Lions Gate Films, and Research In Motion in 2010 and 2011.

11. Clive Davis

    
    Chairman and CEO of Sony Music Entertainment Clive Davis, is one of the most famous producers in music history, signing some of the biggest names in the business, including Pink Floyd, Billy Joel, Bruce Springsteen, Whitney Houston, and Janis Joplin. Five Grammies and an induction into the Rock and Roll Hall of Fame later, Davis is a fixture in the music business and a multi-millionaire. Yet he isn’t content to retire. Seventy-nine year-old Davis is still working full time as a CEO.

12. Henry Kaufman

    
    Born in Germany and forced to flee the Nazis, Kaufman came a long way from his humble beginnings as the son of a butcher. A former Salomon Brothers managing director and board member at Lehman Brothers, Kaufman is a big name in the financial industry, though as of late perhaps not always in a good way (his work at the now defunct firm led to a lawsuit, though it was dismissed). At the age of 82, Kaufman still works full time at his firm Henry Kaufman & Co., and has no plans to retire.

13. Lee Shau Kee

    
    If you know anything about Chinese or international business, you’ve probably heard this billionaire’s name. Kee is the Chairman and Managing Director at Henderson Land Development and the founder and managing director of Henderson Investment. He is the second wealthiest person in Hong Kong and China, and is the 28th richest man in the world. If his investment and real estate endeavors didn’t keep him busy enough, this retirement-phobic 83-year-old also serves on numerous other executive boards.

14. Kirk Kerkorian

    
    Real estate investor Kerkorian is an absolute legend in Las Vegas and Hollywood. Starting his career as a pilot and later owning an airline, Kerkorian is famous for buying huge chunks of the Las Vegas strip, building Caesars Palace, the International Hotel, and the MGM Grand. Kerkorian also bought and sold MGM Studios three times and has, at one time or another, held large stakes in GM, Chrysler, and Ford. Today, the 94-year-old (yes, really) is still president and CEO of Tracinda, his private investment corporation, and spends a great deal of time working with charitable foundations.

15. Sheldon Adelson

    
    Adelson is CEO and Chairman of Las Vegas Sands and, like Kerkorian, he’s a legend in Vegas real estate. He purchased the Sands in 1988, and today the business has gone global, with Sands resorts and casinos in China, the Caribbean, and around the U.S. Adelson was one of the first to pioneer the ideas of the themed mega-resort, in 1991 breaking ground on the Venetian, a hotel that would set the standard for others in Vegas. Today, the still very active Adelson holds a $23.3 billion fortune, but has no plans to leave his position at the Sands.