Country: United States

Allyson Felix won silver medals in Athens (2004) and Beijing (2008) and has her sights set on her first gold medal this year in London. Felix ran the 200-meter sprint in her previous two Olympics. This year she will also run the 100-meter sprint.  If she wins both events, she will become the first female since 1988 to do so.  “I could do something pretty cool,” Felix told TIME.

Country: United States

Archer Brady Ellison is going after his most challenging target yet: an Olympic gold medal. Ellison, who received his first bow at seven years old, has been a competitive archer for over a decade. Now, he’s the top-ranked archer in the world going into the London Games. He was also the first U.S. archer to win three straight World Cups. Ellison, who previously competed at the 2008 Olympics, has a shot this summer at earning Team U.S.A.’s first men’s individual gold medal in the sport since 1996.

Country: Cuba

Dayron Robles hopes to repeat his 2008 Olympic hurdles performance. Just 4 years ago, in Beijing, Robles was awarded the gold medal for the 110-m hurdles after his toughest opponent, Liu Xiang of China, was forced to leave due to injury. The Cuban competitor holds the world record in the 110-m hurdles at 12.87 seconds; however, injuries pose a threat to his speed this summer. Recently, Robles has failed to finish the race in less than 13 seconds. Despite his injuries, Robles will enter the 2012 Olympic games in a strong position and will face off against Liu Xiang.

Country: South Korea

Archer Im Dong Hyun doesn’t let poor vision stop him from making his mark. His vision is so low that he may be considered legally blind, but he doesn’t wear corrective glasses or contact lenses while competing. Instead, he shoots by feel and muscle memory. Dong Hyun, who discovered the sport when he was 10, helped the South Korean archery team win gold at the 2004 and 2008 Olympic Games. Now, going into the London Games, he’s the second-ranked archer in the world behind Brady Ellison. He will be aiming to become the first South Korean to win gold in the Olympic men’s individual event.

Country: Ethiopia

Kenenisa Bekele doesn’t do a lot of interviews and mostly keeps to himself, so he doesn’t always get the attention that other gold medal runners do.  However, Bekele is the most accomplished Ethiopian distance runner at the Olympics. He holds the Olympic and world records for the 5000-meter and 10,000-meter races and won gold medals in both events at the 2008 Olympics.  Bekele might be low-key person, but his performances definitely aren’t.

Country: United States

One of the greatest duos in beach volleyball history, Kerri Walsh-Jennings and Misty May Treanor, are looking to earn their third Olympic gold medal in London.  The two women won Olympic titles for the U.S. in the 2004 and 2008 games, but have not been strong in recent months. Walsh-Jennings was forced to take a break from the game with the births of her two sons in 2009 and 2012. She reunited with Treanor in 2011 and the fierce pair has done everything possible to rebuild the strength they had four years ago. While they are not the top-seated team going to London, the two are looking to bump, set, and spike their way to the gold once again.

Country: Japan

Kohei Uchimura has gymnastics in his blood: His parents and sister are trained gymnasts, too. Competing in the Beijing games at age 19, Uchimura won two silver medals. Since then, he has upped his game, becoming the first male gymnast ever to win three world championships in a row. Known for his precise moves, Uchimura is said to be one of the greatest male gymnasts in the world. This summer, he hopes to use his skills to take home the gold.

Country: People’s Republic of China

Liu Xiang may be hungrier than most Olympic athletes for a gold medal in London this summer. Why? The China native was a champion in the 2004 Olympics and was anticipated to win the 110-m hurdles race in 2008. In a devastating end, however, a foot injury forced the runner to withdraw and leave his potential gold medal behind.  Now, Liu is back in top shape and is ready to compete in the 110-meter hurdles in hopes of winning his second Olympic gold.

Country: United States

Fencer Mariel Zagunis knows how to make the most of an opportunity. After she failed to qualify for the 2004 Olympics, a spot opened up at the last-minute for her. That year, she became the first U.S. fencer in a century to win Olympic gold. She earned another gold for individual saber at the 2008 Games and helped the women’s team win bronze—making her the most decorated U.S. Olympic female fencer. Zagunis has been competing since she was 14 years old. She credits her parents, who were both Olympic rowers, with her success. “I never could have learned so much about life or how to work as hard as I do from any other two people,” she told U.S.A. Fencing. She’ll go for her third straight gold at the London Games.

Country: United States

What do you when you’re the best swimmer in the world? If you’re Michael Phelps, nothing. At the 2008 Beijing Games, in China, Michael Phelps set a record for the most gold medals won at a single Olympics and won the heart of America. But after Beijing, things got rocky. Phelps struggled to get back in the pool. “I just didn’t want to do it. I knew deep down inside I wanted to, but I didn’t want to put in the work,” he says. But now Phelps is back and ready to take on London. If he wins just three more Olympic medals, Phelps will become the most decorated Olympian ever.

To serve as more motivation, it may be his own teammate, Ryan Lochte, who gives Phelps a run for his money this summer. In July, Lochte beat Phelps in two of his gold-medal events, the 200-meter individual medley and the 200-meter freestyle. In London, the rivals will face each other in two events and compete together in the 800-meter freestyle relay. This will be Phelps’ last appearance at the Games, and he wants to make it count. “I want to look back and say I’ve done everything I can in my career,” he says. “If I can say I’ve done everything I wanted, that’s all that matters.”

Country: Germany

This gymnast is no stranger to the Olympics. Her career as an elite gymnast began more than 20 years ago. Oksana participated in her first Olympics in 1992, before many of her competitors were even born. In 2008, she became the first female gymnast ever to compete in five Olympics. A favorite on the vault, she will be returning to her sixth straight Games this summer as part of Germany’s team. She hopes her experience can help secure her team a place in the medal standings.

Country: Tunisia

Tunisia has no shortage of homegrown heroes. After all, it launched the Arab Spring that brought change to many countries. But in London, Tunisian swimmer Ous Mellouli will be making ripples of another kind. Mellouli, 28, will not only defend his 1,500-meter freestyle gold in London, which he won in Beijing; he’ll also race in the 10-k open water event at the Olympics. In early June, he won an open-water Olympic qualifier in Portugal, in just his second competitive open-water race. When asked why was trying to double at the Olympics, Mellouli replied: “Why not?”

Mellouli, who trains in Southern California, left Tunisia at 15 to pursue his Olympic dream. At 24, he became the second Tunisian athlete in history to bring home an Olympic gold medal and the first African male swimmer to ever win an Olympic gold medal in an individual swimming event. After the revolution, he told TunisiaLive leaving home will no longer be necessary. Now, “For that young Tunisian born with ambition, he can make miracles happen.”

Country: Great Britain

At the 2008 Summer Games, Rebecca Adlington became an overnight star. During the preliminary heats of the women’s 800- meter freestyle, she set a new British, Commonwealth, European and Olympic record.  She went on to the Olympic finals to win gold in the 400-meter freestyle and 800-meter freestyle, in which she set a new world record. She also became the first British swimmer in 100 years to win two Olympic gold medals. But, she didn’t stop there. At the 2011 World Championship, Adlington brought home gold in the 800-meter freestyle and silver in the 400-meter freestyle. Expectations are understandably high for the London Games. Adlington fans will be anxiously hoping she can repeat her triumphs in China in 2008. Judging by her performance at the 2012 trials, it will be tough to knock off the Olympic podium.

Country: Switzerland

Roger Federer has been called the greatest tennis player to ever live. Federer is one of seven male players to capture the career Grand Slam and one of three to do so on three different surfaces: clay, grass, and hard court. He has won a record 17 men’s Grand Slam singles titles and has reached Wimbledon finals eight times. At this year’s Wimbledon, he sealed a victory in a championship match against Number 4 ranked Andy Murray. Federer’s win bumped his rank to Number 1 in the world. But, his rivals Novak Djokovic and Rafael Nadal are always close behind.

Luckily for Federer, the Olympics will be held on the same courts he just dominated: Wimbledon. Fans expect his recent victory to carry over to the Olympics, but there’s just one problem: Despite all his success, Federer cannot seem to win gold in an individual Olympic competition. This summer is predicted to be his best chance of breaking that streak.

Country: United States

This summer, Ryan Lochte is the one to keep an eye on in the pool. Lochte may be a six-time Olympic medalist, but he is more famous for being the only man able to beat powerhouse Michael Phelps. Phelps owns the world record in the 400-meter individual medley, but that was four years ago. In the 2012 qualifying finals, Lochte posted the fastest time in the heat, beating Phelps by four seconds. It’s these types of results that have fans expecting an explosive showdown this summer. On the rivalry, Lochte says, “Everyone says that if he wasn’t around, that I would be the greatest swimmer ever. But at the same time, it’s good… We push each other every day.”

Country: Australia

In 2008, Sally Pearson’s silver medal victory in the 100-m hurdles came as a surprise. Another lead racer had fallen over one of the last hurdles and Pearson was able to steal a second-place victory. Now, in 2012, the Australian hurdler, who was named by the International Association of Athletics as female athlete of the year, is in top form. She has won every race she has competed in this year and a gold medal for Sally Pearson is very likely.

Country: United States

Steven Lopez (in blue, above) is part of one big fighting family: two of his siblings, Mark and Diana, are his teammates and another, Jean, is the coach of the U.S. Olympic Taekwondo team.  Steven has been practicing taekwondo since the age of five. He earned gold medals in 2000 and 2004 and a bronze medal in 2008.  He will be trying for his third gold medal in London.

Country: United States

In the 2000 Olympic Games, Gunawan won a gold medal for Indonesia. Since badminton is such a popular sport there, the win was considered to be a very big deal. Gunawan even had to take some time off from the sport due to all the interviews he had to do and the big parade he had to attend. In 2002, he moved to the United States to go to school but continued to coach badminton on the side. Last year, he passed the final test he needed to become a U.S. citizen. Now he and his badminton partner, Howard Bach, are headed to London. They hope bring home a gold medal for Team U.S.A.

Country: Jamaica

There’s no doubt that Usain Bolt is the world’s fastest man. He set world records for the 100-meter and 200-meter sprints in 2009, breaking the records he had set at the 2008 Olympics. Bolt has been honored on and off the track. He received one of his nation’s highest honors when the government awarded him the Order of Jamaica and named him Ambassador at Large.

Country: Russia

Pole vaulter Yelena Isinbayeva took home gold in the last two Olympic Games. But in 2010 and 2011, she did not win any major titles. Then in February, she reversed the trend, breaking the previous world record at a meet in Stockholm, Sweden. She has 28 world records already, and she’s hoping to make it 29 in London. Will Isinbayeva’s success continue this summer? You’ll have to watch to find out!

Click here to view a slide show of athletes making their Olympic debuts at the 2012 Games.