The official retirement age for executives at many large U.S. corporations has been 65 for decades now (unless the executive also happens to be the founder). Just 40 years ago, 65 was considered old; and in 1950, the average life expectancy in was only 68.

Now, even with many sixty-somethings in the prime of their lives, the tradition of CEOs retiring around the age of 65 has not changed at many companies. One reason is that boards of directors want the next generation's management all-stars to take the existing CEOs' place. For example, General Electric's Jack Welch, viewed to be one of the best CEOs of all time, retired at 65. There was no question at the time as to Welch's job performance: The GE board thought three men in the company were CEO material and wanted to elevate one of them. The job went to Jeff Immelt, and the two other men left to run other large corporations.

But rules governing retirement are not applied evenly. At IBM, the mandatory retirement age was 60. Thomas Watson Sr., the de facto founder of IBM, ran the company until just before his death in 1956, at the age of 82. Henry Ford held a number of titles at the company that shared his name. Although he may not have remained the CEO, it is generally accepted that he ran the company until he was forced to hand it over to his grandson. Ford was 81 at the time.

The experiences of Ford and Watson are similar to almost every person on our list. Nearly all of them are either the founder of their company or are related to the founder by blood. All are 75 years of age or older.

Based on our review of publicly available financial information, we created this list of the oldest presidents, chairmen, and CEOs of the Fortune 500 companies. All the men on list have kept the top job at their respective companies long past typical retirement age. The compensation and net worth numbers are based on 2009 data. 

Michael B. Sauter, Ashley C. Allen, and Douglas A. McIntyre are editors of 24/7 Wall St.