Born without fibulas in either leg, Pistorius had both legs amputated below the knee when he was 11 months old. His disability didn’t keep him from competing in rugby, water polo and tennis in school. As he got older, he focused on running.

Pistorius’ remarkable success in able-bodied races has not come without controversy. Some competitors feel the artificial limbs give him an unfair advantage, and the international track federation ruled as such before the 2008 Beijing Olympics. Pistorius challenged the ruling, and it was overturned later that year by the Court of Arbitration for Sport.

Although he was eligible for the 2008 Olympics, he fell short of the qualifying standard. He won gold medals in the 100, 200 and 400 meters at the Paralympics that summer.

•  Hiroshi Hoketsu, equestrian, Japan: Septuagenarians across the globe can rally around Japanese equestrian rider Hoketsu, who at the age of 71 (yes, 71!), will be the oldest competitor in London.

Hoketsu qualified for the individual dressage, riding a 15-year-old horse named Whisper. He first competed in the 1964 Games when he was 23. He was 67 when he finished ninth in the team event and 35th as an individual at the Beijing Olympics four years ago. Back home in Japan, they call him “The Hope of Old Men.”

He has an endorsement deal with a health food chain and continues to train twice a day.

Believe it or not, Hoketsu is not the oldest Olympian in history. Swedish shooter Oscar Swahn was 72 when he won a silver medal at the 1920 Olympics in Antwerp.

•  Aliya Mustafina, gymnastics, Russia, and Larisa Iordache, gymnastics, Romania: Every Olympics needs its gymnastics pixies, and this time, two to watch are Russian teen Mustafina and Romanian teen Iordache.

Mustafina won the 2010 all-around world championship at age 15 and was favored to win the 2001 European championship. But she tore the ACL of her left knee on the landing of a difficult vault and was carried off the podium, reminiscent of the Kerri Strug vault injury at the 1996 Atlanta Olympics.

She had surgery and did not compete for eight months. She started training again in December 2011, and though she has struggled in her first few meets, she is considered one of the favorites.

Also watch for Iordache, 15, who has drawn comparisons to Nadia Comaneci, the tiny Romanian who won the 1976 gold. Iordache won the gold in floor exercise and silver in beam at the recent world championships.

•  Chris Hoy, track cycling, Great Britain: They call Chris Hoy “The Real McHoy.”

The Scottish track cyclist won three gold medals in Beijing and was knighted Sir Chris by Queen Elizabeth II in 2009. He is on pace to become Great Britain’s most successful Olympian, as he has collected four golds and a silver. Rowing legend Steve Redgrave holds the national record with five golds and a bronze. Hoy is the first Briton to win three gold medals in a single Olympics since freestyle swimmer Henry Taylor in 1908.

Caster Semenya, track and field, South Africa: Doubts about her gender made life miserable for South African runner Semenya three years ago, but she said she has put it behind her and if she wins a medal, she will dedicate it to Nelson Mandela, who helped her during her tough times.

When Semenya, 19, won the 800-meter world title in 2009, skeptics insisted she was not a woman, and she was forced to undergo testing.