There are plenty of energy companies ranked in this year's Fortune 500. In a testament to the money-making muscle of the oil industry, three of the top five companies are oil and gas majors. Over the past 10 years, these companies have solidified their status as perennial winners and remain strong candidates for investors' portfolios.

No. 1 -- ExxonMobil (NYSE: XOM)
For all the "who's bigger" talk surrounding ExxonMobil, Apple (Nasdaq: AAPL), and their respective market caps, when it comes to profit and revenue there is no competition. Exxon recorded more than $41 billion in profit, while Apple, coming in at 17 on Fortune's list, made just shy of $26 billion. In fact, Exxon's real rival for the No. 1 position is Wal-Mart (NYSE: WMT). The two companies have traded Fortune's No. 1 ranking on and off since 2004.

Exxon recorded record revenue in 2011, its $453 billion surpassing 2008's $443 billion. However, the company's profit of $41 billion didn't match 2008's $45 billion.

No. 3 -- Chevron (NYSE: CVX)
This is the fifth straight year that Chevron ranks third on Fortune's list. The company has quite a way to go to overcome either Exxon or Wal-Mart for a higher ranking: Its $245 billion in revenue is nowhere near Exxon's $453 billion or Wal-Mart's $447 billion.

The company is improving, however. Though 2011 revenue failed to return to its 2008 peak, 2011 profits of $26.8 billion surpassed 2008's $23.9 billion.

No. 4 -- ConocoPhillips (NYSE: COP)
ConocoPhillips has come a long way since its No. 12 ranking in 2003. Breaking into the top 10 the following year, the company has slowly increased its profit from $8.1 billion in 2004 to $12.4 billion, overcoming a nearly $17 billion loss in 2008. Though their profits also declined between 2008 and 2009, neither Exxon nor Chevron recorded a loss during that time.

This is ConocoPhillips' second straight year ranked fourth on the list.

Foolish takeaway
Just because a company makes a lot of money and lands on Fortune's list, doesn't guarantee it will generate impressive returns for shareholders. That being said, two of this year's top five companies are among the nine stocks Fool analysts have outlined as smart investments to include in a retirement portfolio because of their strong dividends.