Now that the 2012 Summer Olympics are here, let's take a look back at five astonishing examples of American triumph from Summer Olympic Games from the past:

1. 1936, Berlin: Jesse Owens Sticks It To Hitler

Just a few years before the outbreak of WWII, the Olympic Games in Berlin were a way for Hitler to illustrate the supremacy of the Nazi regime. But much to the Fuhrer's chagrin, it was a black athlete, the son of an Alabaman sharecropper, who became the star of the summer games that year.

Jesse Owens, the grandson of slaves, won four gold medals that summer in Berlin: one for the 100-meter dash, one for the 200-meter dash, one for the long jump, and one as part of the 4x100 meter relay team. Although Hitler left the ceremony without congratulating the victors, Owens said that Hitler waved at him before he departed. Owens waved back.

But later, a close adviser to Hitler revealed in a memoir that the Fuhrer was “highly annoyed” that a black man had won four gold medals.

2. 1972, Munich: Mark Spitz Wins 7 Gold Medals, Sets 7 World Records

Mark Spitz, an American swimmer from California, began training at a very young age. His family moved several times so that Spitz could learn from the best coaches money could buy. "Swimming isn't everything--winning is,” his father told him. Before he turned 19, Spitz had set 10 world records.

In the 1972 Summer Olympics in Munich, Spitz won the gold medal for seven races, including two team relays. After his sixth gold medal, Spitz nearly pulled out of the 100 meter freestyle race, because he was afraid he’d lose to his teammate Jerry Heidenreich. He told a reporter for ABC News, “If I swim six and win six, I’ll be a hero. If I swim seven and win six, I’ll be a failure.” But despite his anxieties Spitz beat Heidenreich by a half-stroke for his seventh gold medal.

Spitz was the first person to win 7 gold medals. The previous record had been set by at Italian fencer at the 1920 Summer Olympics in Antwerp, Belgium.

But before he could even start to savor his victory, terror struck. At dawn on the morning of September 5, a group of Palestinian terrorists snuck into the Olympic Village and murdered two Israelis and took another nine hostage, who would later be killed in a botched rescue attempt. Spitz, who was Jewish, was brought to the airport under armed guard and immediately flown to London. His victories were promptly forgotten in light of the hostage crisis, but his record for the number of gold medals won stood for 36 years, until Michael Phelps broke it in Beijing in 2008.

3. 1988, Seoul: Greg Louganis Sets Record In Diving Despite Head Injury

Greg Louganis, an adopted child who struggled with asthma, dyslexia and depression as a child, even attempting suicide multiple times, went on to pull off one of the most amazing Olympic feats in American history.

During the qualifying contest for the 3-meter springboard event, Louganis hit his head on the board, resulting in a concussion and a dangerous gash that had to be stitched immediately. Nevertheless, just a half hour later, Louganis nailed a difficult dive--reverse somersault with three twists. His score was higher than any diver had ever earned for a single dive in the qualifying round.

The next day, in spite of his injury, Louganis headed to the finals and won the gold medal for the springboard competition, despite being up against competitors who were half his age. Shortly afterwards, Louganis also won the gold medal for the platform dive.

Louganis was the first man to win back-to-back Olympic gold medals in the platform and springboard events. To this day, that record has not been equaled.

Louganis later revealed that he was gay and that he was HIV positive--a fact he’d learned just months before the 1988 Olympic games.

4. 1996, Atlanta: US Beats Reigning Champs For First Gold Ever In Team Gymnastics

Going into the Summer Games of 1996, the United States had never won a gold medal in the team gymnastics event. Russia had dominated it for decades. But Kerri Strug--an unassuming athlete, only 4’9” tall, who had a reputation for cracking under pressure, changed history that year.

Although the US had a good lead on the Russians going into the vault, their lead quickly disappeared when the first four American gymnasts failed to land cleanly. It appeared the US would lose yet again to Russia. To make matters worse, Strug fell on her first vault and hurt her ankle.

But in spite of her injury, Strug completed a difficult second vault, earning a score high enough to secure the gold medal for the US for the first time in history. Strug was featured on the cover of Sports Illustrated, personally congratulated by President Clinton, and appeared (with the rest of her team) on a Wheaties Box.

She was hailed as a national hero, despite the fact that, in retrospect, it was determined that her second vault was not necessary for the United States to win the gold medal.

5. 2000, Sydney: Underdog Rulon Gardner Beats Longtime Siberian Champion In Greco Roman Wrestling

How an unknown wrestler from a dairy farm in western Wyoming came to beat a massive Russian heavyweight who had held the title for 13 years, is the stuff of legend.

Alexander Karelin, who is from Siberia, was known as a “one-man dynasty.” He had won three Olympic Gold medals in a row. He hadn’t given up a single point in six years. He once carried a refrigerator up seven flights of stairs by himself.

Rulon Gardner, by comparison, had never won a medal in any international competition. Very few thought he could survive Karelin’s brutal reverse body lift, a move Karelin was famous for and which he had used to defeat Gardner just three years before.

But Gardner had a strategy of his own--to wear out his opponent. “If I could get him tired, I could have an opportunity to defeat him,” Gardner said. To his advantage, Karelin had already competed in two matches that day, while Gardner had only performed in one.

Sure enough--after Gardner had gained a one-point lead--Karelin began to show signs of fatigue. The match went into overtime, and Gardner was able to hold onto his lead as the clock ran out. Gardner did cartwheels and somersaults and ran around the mat with an American flag in his hands as an announcer stated the obvious: “Rulon Gardner has shocked the wrestling world.”