Samuel Wanjiru

Wanjiru started running at the age of 8. In 2002, he moved to Japan and went to Sendai Ikuei Gakuen High School in Sendai. He had success on the Japanese cross country circuit, where he won the Fukuoka International Cross Country at sixteen years old in 2003. He went on to win in both Fukuoka and at the Chiba International Cross Country consecutively in 2004 and 2005. After graduating in 2005, he joined the Toyota Kyūshū athletics team, coached by 1992 Olympic marathon silver medalist Koichi Morishita.

Wanjiru had a 5000 m best of 13:12.40, run as a 17-year-old in April 2004 in Hiroshima, Japan. At age 18, Wanjiru broke the half marathon world record on 11 September 2005 in the Rotterdam Half Marathon with a time of 59:16 minutes, officially beating Paul Tergat's half-marathon record of 59:17 minutes.

Wanjiru took back the half-marathon world record, which Haile Gebrselassie broke in early 2006, with 58:53 minutes on 9 February 2007 at the Ras Al Khaimah Half Marathon and improved it to 58:33 on 17 March 2007 in the City-Pier-City Loop in The Hague, Netherlands. While improving his own record, he recorded an unofficial time of 55:31 for 20 km, which was faster than Haile Gebrselassie's world record but was never ratified due to the timing methods in the race.

Wanjiru made his marathon debut at Fukuoka Marathon on 2 December 2007, winning it impressively with a course record of 2:06:39. He started 2008 by winning the Zayed International Half Marathon and receiving a prize of US$300,000. In the 2008 London Marathon, he came in second, breaking 2:06 for the first time. In the 2008 Summer Olympics, Wanjiru won the marathon gold medal in an Olympic record time of 2:06:32, smashing the previous record of 2:09:21 set by Carlos Lopes of Portugal in the 1984 Olympics. He received the AIMS World Athlete of the Year Award that year in recognition of his performances.

At the Granollers Half Marathon in February 2008, in which Wanjiru won, the Kenyan stated his intent for the future, saying, "in five years' time I feel capable of clocking a sub 2 hours time for the marathon." In April 2009, Wanjiru won the London Marathon in a time of 2:05:10, a new personal record and also a new course record. He was pleased with the achievement and stated that he hoped to break Haile Gebrselassie's world record in the near future. At the Rotterdam Half Marathon, Wanjiru clocked a 1:01:08 on 13 September, which was won by Sammy Kitwara with a time of 58:58. In October 2009, Wanjiru won the Chicago Marathon in a time of 2:05:41, setting a new course record for the city and the fastest marathon time ever run in the United States. The wins in London and Chicago helped him reach the top of the World Marathon Majors rankings for 2009, earning him a jackpot of US$500,000.

Wanjiru married Mary Wacera, a fellow long-distance runner, in 2009 and the two had a child (Ann) in 2010. He had previously married Triza Njeri in a traditional ceremony and had two children, although Wanjiru and Wacera's marriage was legally binding.

In December 2010 Wanjiru was arrested by Kenyan police at his house in Nyahururu and charged with threatening to kill his wife and illegally possessing an AK-47 rifle. He denied both the accusations and claimed that he was being framed.

On 15 May 2011, Wanjiru died from a fall off a balcony at his home in Nyahururu. Wanjiru appeared to have suffered internal injuries after the fall and was confirmed dead by doctors at a nearby hospital after attempts to revive him failed.

In May 2017, while testifying during an inquest into Wanjiru's death, his mother Hannah Wanjiru said at the Milimani law court that she believes her son was murdered.