When the sovereign debt crisis first swept through Europe, almost every stock got pummeled, but the banking sector got hit especially hard. And rightfully so -- almost no one knew what was on the balance sheets of the big institutions, and billions of dollars of federal liabilities had to sit somewhere.

As such, countries such as Greece, Italy, Spain, and Ireland saw stocks drop quicker than a Tony Romo fumble. But oh how things have changed. The bank I'm about to suggest may absolutely shock you.

Introduce yourself to Spain
Banco Santander (NYSE: STD) is Spain's largest bank, with a 153-year history. It has more than 192 million customers and is the largest euro-denominated bank. Although it has seen a nice rebound in the past few months, its shares are down 17% so far this year.

But this is one bank you want to own -- today, if possible.

Santander managed 2008's financial crisis without so much as a flinch, experiencing not even one unprofitable quarter -- compared to America's banks, you get a sense of how amazing that really is. One of the reasons is that the bank, as part of Spain's mandatory regulations, is forced to hold very high reserves to cover any unforeseen losses. It also avoided U.S. subprime debt as part of its inherently conservative nature. In 2009, it earned $10.9 billion in profit and is expected to earn at least the same amount in 2010; in comparison, JPMorgan Chase (NYSE: JPM) earned just more than $11.7 billion that same year.

In addition, it recently passed the EU stress tests with flying colors. Its core tier 1 ratio was reported to be 10% at the end of 2009. Under the adverse scenario, it rose to 10.2%, and in the adverse scenario plus a sovereign debt "shock," the ratio only fell back down to 10%. That's pretty impressive. Did I mention that the bank's price-to-earnings multiple is a paltry 10.2, and it's only trading slightly above book value? Sure, there are other European banks that are cheap as well -- National Bank of Greece (NYSE: NBG), Bank of Ireland (NYSE: IRE), and Allied Irish Banks (NYSE: AIB) all come to mind. But Allied Irish, despite passing the stress tests, still needs to raise $9.7 billion by the end of the year. Failing to do so would mean the government would have to act as a backstop. Bank of Ireland has said that in the worst-case scenario, its tier 1 would be 7.1%, nowhere near as good as Santander's. National Bank of Greece actually trades slightly above Banco Santander's prices and also has quite a bit more uncertainty surrounding it.

Head and shoulders above the rest
Despite the naysayers and the doubters, Banco Santander is marching ahead like it's nobody's business. It's currently bidding for 300 U.K. branches of Royal Bank of Scotland. A few months ago it agreed to buy back almost 25% of its Mexican unit from Bank of America (NYSE: BAC), and it also purchased $3.2 billion of auto loans from Citigroup (NYSE: C).

It has added $36.6 billion in deposits this year, just as its largest competitor, Banco Bilbao Vizcaya Argentaria, saw deposits drop by 6.9%. It's stealing market share left and right by offering above-average interest rates, and it continues to expand in its home country as well as abroad. This year will be the first time that the bank will earn more profit from Brazil than from Spain.

The Foolish bottom line
Banco Santander is on an absolute tear right now. Neither the financial crisis that crippled our entire economic system, nor the Spanish recession, has been able to keep it down. Emilio Botin, the 75-year-old CEO, doesn't seem to care what the markets think or expect of him. He just keeps being the aggressive executive that he has always been, having grown the bank from one with 700,000 customers to the near 100 million that it has today. Juan Inciarte, the bank's head of strategy, put it best by saying that growth and diversification are "in the DNA" of the bank.

Clearly, that DNA has created one successful bank. I suggest you scoop up shares before it's already too late.

Disagree with me? Let me hear it in the comment section below!

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.