Garrett James Hardin was an American ecologist and microbiologist. He focused his career on the issue of human overpopulation, and is best known for his exposition of the tragedy of the commons in a 1968 paper of the same title in Science, which called attention to "the damage that innocent actions by individuals can inflict on the environment". He is also known for Hardin's First Law of Human Ecology: "We can never do merely one thing. Any intrusion into nature has numerous effects, many of which are unpredictable."

The tragedy of the commons is a metaphoric label for a concept that is widely discussed, and criticised, in economics, ecology and other sciences. According to the concept, should a number of people enjoy unfettered access to a finite, valuable resource such as a pasture, they will tend to over-use it, and may end up destroying its value altogether. Even if some users exercised voluntary restraint, the other users would merely supplant them, the predictable result being a tragedy for all.