The 2012 London Olympics are set to kick off July 27, with some new (and old) athletes looking to make their mark on history.
Since 1896, there have been hundreds of athletes who have made their marks and endeared themselves to millions of fans around the world.
Some overcame tremendous odds to win a gold medal, while others were so good that they won a lot of medals during their career.
Here's a look at 30 of those athletes who I consider to be the greatest in Summer Olympics history.
Note: Over the course of more than 100 years of Olympics and tens of thousands of athletes, undoubtedly there will be some that are missed or forgotten about. Still, these 30 athletes are in my opinion some of the greatest ever.
Frank Kugler is the only athlete in Olympic history to win a medal in three different sports.
In the 1904 Olympics, he won a silver medal in men's freestyle wrestling, and bronze medals in two-hand lift, all-around dumbell and team tug-o-war.
For that, he deserves at least a spot in the rankings, because no athlete has ever accomplished that feat besides him.
Wilma Rudolph was a bronze medalist in the 1956 Olympics in the 400-meter relay at 16 years old in track and field.
At the 1960 Olympics in Rome, she won gold medals in the 100 meters, 200 meters and 400-meter relay, as she earned the nickname "The Tornado."
Other nicknames she was given included La Gazzella Negra (The Black Gazelle) by the Italians and La Perle Noire (The Black Pearl) by the French.
Daley Thompson competed for Great Britain in the 1980 and 1984 Olympics.
During those Olympics, he won the gold medal in the decathlon both times, meaning he was the best all-around track and field athlete at both Olympics.
In 1988, he was again one of the top competitors, but he ended up finishing fourth.
The only problem with Thompson's gold medals is that they came during boycotted Games, with top U.S. competitors out of the 1980 Games and top Soviet-bloc athletes staying home in 1984. However, he did set world records during that stretch of years and he won the 1983 world championship.
Bob Mathias won Olympic gold at the 1948 and 1952 Summer Olympics in track and field at the ages of 18 and 22 during those Olympics.
In 1952, he won the decathlon by 912 points, which was the largest margin of victory in the decathlon up to that time.
For five consecutive Olympics, Sir Steven Redgrave won a gold medal in rowing at the Olympics.
Redgrave won gold in the coxed four in 1984 and 2000, while he also won golds in the coxless pairs in 1988, 1992 and 1996. He also took home a bronze in the coxed four in 1988.
To be that consistent over that period of time makes him one of the best, if not the best Olympic rower of all time.
Had the U.S. not boycotted the 1980 Olympics in Moscow, Louganis would most definitely be higher on the list.
Still, four golds and a silver medal in diving is nothing to bat your eye at.
At 16 years old, he won silver in 1976 in the 10m platform, while taking gold in the 3m springboard and 10m platform at both the 1984 and 1988 Olympics.
However, in 1988, his gold came close to not happening after he hit his head on the springboard during the preliminary rounds. Louganis was able to recover from the concussion and went on to win the gold medal.
Years later, when Louganis co-wrote his autobiography, Breaking the Surface, he revealed he found out he was HIV-positive weeks before the 1988 Olympics, causing ire among the diving community that he would put his opponents at risk.
Louganis stands as one of the best divers of all time, despite the incident.
Regarded as the greatest swordsman ever by CNN, Aladar Gerevich won a gold medal at six straight Olympics, with the war-torn years being in the middle.
In the 1932 and 1936 Olympics, he won gold as part of the sabre team and bronze in sabre individual in 1936, then had to wait as no Olympics were contested in 1940 and 1944 because of World War II.
However, Gerevich remained on top after the war, winning gold in sabre team and sabre individual in 1948, gold in sabre team and silver in sabre individual in 1952 and sabre team golds in 1956 and 1960.
Prior to the 1960 Olympics, Gerevich was told he was too old by the Hungarian Olympic Committee. He responded by challenging all of the members of the sabre team, defeating each one of them.
Due to more television exposure and ability for endorsement deals, Jackie Joyner-Kersee took women's track and field to the next level.
She has a record of three golds, one silver and two bronzes in the Olympics.
Beginning her Olympic career in 1984, Joyner-Kersee took silver in the heptathlon. In 1988, she won double gold in the heptathlon and long jump.
In 1992, she won gold again the heptathlon and bronze in the long jump, finishing out her Olympic career in 1996 with a bronze in the long jump.
Her 1988 heptathlon gold set a world record with 7,291 points, a record that still stands today.
During the 1920s, Paavo Nurmi was considered the best middle- and long-distance runner in the world.
From 1920-1928, Nurmi won nine gold and three silver medals in Olympic competition.
In particular, he won five individual gold medals in the 1924 Olympics, winning the 1,500 meters, 5,000 meters, individual cross-country, 5,000 meter cross-country team and 3,000 meter team.
Unfortunately, Nurmi was unable to run in the 1932 Olympics because he received money for his running, thus making him a professional.
Still, his 12 track and field medals stand as an Olympic record for the sport to this day.
Ray Ewry won eight gold medals in the Olympics, and two gold medals in the Intercalated Games, which is no longer counted in the Olympic total.
Ewry won gold in the standing long jump (1900, 1904 and 1908), standing high jump (1900, 1904 and 1908) and standing triple jump (1900 and 1904).
And all this was after he contracted polio as a child, which relegated him to a wheelchair, but not for the rest of his life like doctors feared when he originally contracted the illness.
Birgit Fischer won eight golds and four silvers during her Olympic kayaking career.
As a member of the East German team, she won gold in K-1 500 meters (1980), K-2 500 meters (1988) and K-4 500 meters (1988) and a silver in the K-1 500 meters (1988).
After the fall of the Berlin Wall and Germany again became one, Fischer won five more golds and three silvers.
In 1992, she won gold in K-1 500 meters and silver in K-4 500 meters; in 1996 she won gold in K-4 500 meters and silver in K-2 500 meters; in 2000 she won double gold in K-2 500 meters and K-4 500 meters; in 2004, she won gold in K-4 500 meters and silver in K-2 500 meters.
Her 12 medals make her the most successful Olympic kayaking athlete of all time.
With 13 overall Olympic medals, Edoardo Mangiarotti is one of the most successful fencers of all time.
In 1936, 1952, 1956 and 1960, he won a gold in team epee, while also winning gold in the individual epee in 1952 and gold in the team foil in 1956.
His silver medals came in the team foil (1948, 1952 and 1960), team epee in 1948 and individual foil in 1952.
Finally, he won two individual epee bronze medals in the 1948 and 1956 Olympics.
Fanny Blankers-Koen is best known for winning four gold medals at the 1948 Olympics.
Her victories came in the 100-meters, 200-meters, 80-meter hurdles and 400-meter relay.
Raising two children, while training for the Olympics, earned her the nickname "The Flying Housewife."
Later, it was found out (after giving birth to her third child in early 1949), she had won those four gold medals while pregnant.
Quick, name me the last woman to win four gold medals while pregnant?
Yeah, I need some time on it, too.
Edwin Moses is mostly known for having not lost a 400-meter hurdle race over the course of nine years, or 122 races.
His Olympic record may not look as stunning as others, with two golds and one bronze, but he still has to be considered one of the best of all time.
In 1976, in his first international competition, Moses won the gold medal and set a world record for the event at 47.63 seconds.
As of today, he still holds 25 of the fastest 100 400-meter hurdle times ever.
For all intents and purposes, Vera Čáslavská should be higher on this list.
She racked up a total of seven golds and four silvers between 1960 and 1968.
In 1960, she won silver in the team event.
But the 1964 Olympics was her coming out party, as she won gold in in the individual all-around, vault and balance beam, and a silver in the team event.
In the 1968 Olympics, she won gold in the individual all-around, vault, uneven bars and floor exercise, while taking silver in the balance beam and team competition.
But the Czechoslovakian gymnast was very outspoken in her views about Soviet-style communism during the 1968 Olympics.
While at the Olympics, she continued to voice her views, which may have cost her a few titles. After having appeared to win the gold on the floor exercise, the judging panel upgraded the preliminary scores for Soviet Larisa Petrk, declaring a tie for the gold.
This happened on the heels of another controversial decision in which Čáslavská lost the gold on the beam to Natalia Kuchinskaya. In a display of anger towards the politics she felt favored the USSR, she protested both medal ceremonies by turning her head down and away during the playing of the Soviet national anthem.
Until 1980, Boris Shakhlin held the record for most Olympic medals for one athlete.
In 1956, he won gold in the team competition and pommel horse.
In the 1960 Olympics, he won a total of seven medals, including gold in the all-around, pommel horse, vault and parallel bars, while also winning silver in the team competition and rings and bronze in the horizontal bar.
In 1964, he won gold in the horizontal bar, silver in the team competition and all-around and bronze in the rings.
Viktor Chukarin was the first of the great Soviet gymnasts.
He won 11 total Olympic medals, including seven golds.
In 1952, he won gold in the team competition, all-around, pommel horse and vault, while also winning silver in the rings and parallel bars.
In 1956, he won gold in the team competition, all-around and parallel bars, while winning a silver on the floor exercise and bronze on the pommel horse.
After Mark Spitz, the next great American swimmer was Matt Biondi.
In 1984, he won gold in the 400-meter freestyle relay.
In 1988, he won seven medals, including five golds. His golds came in the 50-meter and 100-meter freestyles, 400-meter freestyle relay, 800-meter freestyle relay and 400-meter medley relay. His silver medal came in the 100-meter butterfly, with his bronze coming in the 200-meter freestyle.
His two gold medals in 1992 came in the 400-meter freestyle and 400-meter medley relays, while winning a silver in the 50-meter freestyle.
When I first started watching the Olympics as a kid, I can remember hearing the name Alexei Nemov.
Nemov won all 12 of his medals in the 1996 and 2000 Olympics.
In 1996, he won gold in the team event and the vault, silver in the all-around and bronze in the floor exercise, high bar and pommel horse.
In 2000, he won gold in the all-around and high bar, silver in the floor exercise and bronze in the team competition, pommel horse and parallel bars.
In my opinion, he should go down as the greatest male Russian gymnast of all time.
Natalie Coughlin is an 11-time Olympic medalist for the United States, and she's going after more medals this year.
She became the first woman ever to win six medals at one Olympics, and the first woman ever to win the 100-meter backstroke at two separate Olympics.
Coughlin took home five medals in the 2004 Olympics, including gold in the 100-meter backstroke and 800-meter freestyle relay, while taking home silver in the 400-meter freestyle and 400-meter medley relays. She also brought home a bronze in the 100-meter freestyle.
In 2008, Coughlin again took gold in the 100-meter backstroke, while also taking home silver in the 400-meter freestyle and 400-meter medley relays. She also earned three bronze medals in the 100-meter freestyle, 200-meter individual medley and 800-meter freestyle relay.
Her consistency at or near the top over those two Olympics warrants her this selection.
In three Olympics, Sawao Kato won 12 medals in gymnastics for Japan.
Kato started competing in 1968, when he took gold in the team event, all-around, floor exercise and bronze in the rings.
In 1972, he won gold in the team event, all-around and parallel bars, while taking silver in the horizontal bar and pommel horse.
Kato fell short in the 1976 Olympics in the all-around as he fell to the Soviet Union's Nikolai Andrianov, but he did take gold in the team competition and parallel bars.
Kato is one of 10 athletes to have won eight or more gold medals, becoming one of the most decorated male gymnasts in history, and the most decorated Japanese athlete in Olympic history.
Nadia Comaneci is best known for scoring the first perfect 10 ever in Olympic gymnastics.
During her time in the Olympics, she won five golds, three silvers and one bronze.
In the 1976 Olympics, during the team competition in which Romania was on the uneven bars, Comaneci scored her perfect 10.
At those Olympics, she won gold in the all-around, uneven bars and balance beam, while winning silver in the team competition and bronze on the floor exercise.
In 1980, she won gold on the balance beam and floor exercise, while winning silver in the team competition and all-around.
Kristin Otto competed in only one Olympics (1988) for East Germany.
In that one Olympics, she won six gold medals, dominating her competition.
The events she won were the 50-meter and 100-meter freestyle, 100-meter butterfly, 100-meter backstroke and the 400-meter freestyle and 400-meter medley relays.
Possibly considered the best all-around athlete in the history of the modern world, and although he only competed in one Olympics, he was still very dominant in those Olympics.
He won gold in the pentathlon and decathlon in the 1912 Olympics.
However, in 1913, strict rules regarding amateurism were put into effect for Olympic athletes.
Because Thorpe had been paid money to play baseball, although a very meager amount, he was no longer considered an amateur, and thus declared ineligible to compete in the Olympics.
Nikolay Andrianov was the most successful male Olympic athlete, well, until Michael Phelps came along.
Andrianov started his Olympic reign in 1972 in which he won gold in the floor exercise, silver in the team competition and bronze in the vault.
In 1976, he won gold in the all-around, floor exercise, rings and vault, also winning silver in the team competition and parallel bars and bronze on the pommel horse.
For the 1980 Olympics, he won gold in the team competition and vault, silver in the all-around and floor exercise and bronze on the horizontal bar.
Jesse Owens pulled off four gold medals under incredible pressure at the Berlin Games in 1936.
German leader Adolf Hitler saw the Games as a chance to show Aryans to be the "master race."
Boy, did Owens show him.
Owens took gold in the 100 meters, 200 meters, long jump and 400-meter relay.
The long jump victory came on the heels of advice given to him by Luz Long, the German competitor he ultimately defeated.
Mark Spitz held the record for most gold medals in a single Olympics, winning seven.
That record stood until Michael Phelps broke it in the 2008 Olympics.
His victories came in the 100-meter butterfly, 100-meter freestyle, 200-meter butterfly, 200-meter freestyle, 400-meter freestyle relay, 400-meter medley relay and 800-meter freestyle relay.
Prior to that, he won two golds, a silver and a bronze in the 1968 Mexico City Olympics.
His golds came in the 400- and 800-meter freestyle relays, while he won silver in the 100-meter butterfly and bronze in the 100-meter freestyle
When it came to being the first high-endurance athlete at a single Olympics, Spitz was that guy.
And without his record-setting performance, I wonder if Phelps would have been driven so much to go for eight golds.
Carl Lewis is the greatest track and field athlete in Olympic history.
He was an Olympic mainstay from 1984 to 1996.
In 1984, he won gold in the 100 meters, 200 meters, long jump and 400-meter relay.
In the 1988 Olympics in Seoul, he took gold in the 100 meters and long jump, while taking a silver in the 200 meters.
At the 1992 Olympics, he won gold in the 400-meter relay and long jump, finishing out his career in the 1996 Atlanta Olympics with a gold in the long jump.
Never before has an athlete dominated for so long at so many events in Olympic track and field.
Had it not been for the next two, he would be the greatest Olympic athlete of all time.
Larisa Semyonovna Latynina holds the record for most overall Olympic medals with 18 in gymnastics.
She was responsible for establishing the Soviet Union's dominance in gymnastics.
In 1956, she won gold medals in the team competition, all-around, floor exercise and vault, while taking the silver medal on the uneven bars and the bronze in the team event with portable apparatus.
In the 1960 Rome Olympics, Latynina won gold in the team event, all-around, floor exercise, she took silver in the balance beam and uneven bars and the bronze in the vault.
She competed as well in the 1964 Olympics, although she was not as successful.
Her final total before retiring was nine golds, five silvers and four bronzes.
Michael Phelps is without a doubt the best Olympic athlete in history.
Not only did he win eight gold medals in the 2008 Olympics in Beijing, he also won six gold medals and two bronze medals in the 2004 Olympics.
Those eight gold medals eclipsed Mark Spitz's record of seven in the 1972 Munich Olympics.
He already holds the record for the most gold medals in the Olympics, and with three more medals in London, he'll become the most decorated Olympic athlete in history.
I think Mark Spitz said it best:
Epic. It goes to show you that not only is this guy the greatest swimmer of all time and the greatest Olympian of all time, he's maybe the greatest athlete of all time. He's the greatest racer who ever walked the planet.
Now, when a guy like Mark Spitz is saying that, you better believe it's true.