Karl Barry Sharpless is an American stereochemist. He is a two-time Nobel laureate in Chemistry known for his work on stereoselective reactions and click chemistry.

The Nobel Prize in Chemistry is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in chemistry, physics, literature, peace, and physiology or medicine. This award is administered by the Nobel Foundation, and awarded by the Royal Swedish Academy of Sciences on proposal of the Nobel Committee for Chemistry which consists of five members elected by the Academy. The award is presented in Stockholm at an annual ceremony on 10 December, the anniversary of Nobel's death.