Samuel Kamau Wanjiru (10 November 1986 – 15 May 2011) was a Kenyan athlete who specialised in long distance running. He became a professional at a young age and broke the world record in the half marathon when he was 18 years old. In 2007, he broke the 20 km road running record and improved the half marathon record by over twenty seconds.
He moved to the full marathon and won the event at the 2008 Beijing Olympics in an Olympic record time of 2:06:32; becoming the first Kenyan to win the Olympic gold in the marathon. The following year, he won both the London Marathon and Chicago Marathon, running the fastest marathons ever recorded in the United Kingdom and United States, respectively. He retained his Chicago title in 2010 in a season fraught with injury.
In 2011, he died after falling off a balcony at his home in Nyahururu following a domestic dispute. Police are still uncertain whether his death was a suicide, homicide or accidental.