Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American chemist, biochemist, chemical engineer, peace activist, writer and educator, one of most important and influential scientists of the 20th century for his groundbreaking contributions to the fields of chemistry, physics and biology.

He has published more than 1,200 studies and books, including about 850 on scientific topics. New Scientist magazine listed him as one of the 20 greatest scientists of all time, and in 2000 he was the 16th most important scientist in history. For his scientific work, Pauling received the Nobel Prize in Chemistry in 1954. He also received the Nobel Peace Prize in 1962 for his peace activism.

Pauling was born in Portland, Oregon, in 1901. He studied chemistry at Oregon State University and the California Institute of Technology, where he earned his Ph.D. in 1925. After a brief stint working in industry, he returned to academia, first at the University of California, Berkeley, and then at the Carnegie Institution in Washington, D.C.

It was during this period that Pauling made his most important scientific discoveries. He developed a new theory of the chemical bond, which revolutionized our understanding of how molecules are held together. He also pioneered the study of molecular biology, and was the first to suggest that sickle cell anemia was caused by a mutation in a single gene.

In 1954, Pauling was awarded the Nobel Prize in Chemistry, in recognition of his “research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances.” He is the only person to have won two unshared Nobel Prizes (the other being the Nobel Peace Prize, which he received in 1962).

Pauling continued to work until his death in 1994. His legacy is one of immense scientific accomplishment, and his work has had a profound impact on the world we live in today.