Ernst Haeckel coined the term "ecology" and is considered the Father of Ecology.

Rachel Carson's book "Silent Spring" brought attention to the harmful effects of pesticides on the environment.

John Muir founded the Sierra Club in 1892 to protect the Sierra Nevada mountains and promote conservation.

Aldo Leopold's land ethic philosophy advocates for a harmonious relationship between humans and the environment.

David Brower was a leading environmental activist and founder of Friends of the Earth, an international environmental organization.

Paul Ehrlich is known for his work on population control and environmental sustainability, particularly through his book "The Population Bomb".

Barry Commoner is an environmental scientist and author known for his book "The Closing Circle", which addresses environmental issues and the need for sustainable practices.

Amory Lovins is known for his work on energy efficiency and sustainable technologies, particularly through his book "Soft Energy Paths".

James Lovelock is an environmental scientist and author known for his Gaia hypothesis, which proposes that the Earth is a self-regulating system.

Wangari Maathai is a Kenyan environmental and political activist known for her work on reforestation and sustainable development, particularly through the Green Belt Movement.

Vandana Shiva is an Indian environmental activist and author known for her work on biodiversity, sustainable agriculture, and the rights of indigenous communities.

Chico Mendes was a Brazilian environmental activist and trade union leader known for his work on protecting the Amazon rainforest and the rights of rubber tappers.

Ken Saro-Wiwa was a Nigerian environmental activist and writer known for his work on the environmental impacts of oil production in the Niger Delta and the rights of the Ogoni people.

Greta Thunberg is a Swedish environmental activist known for her work on climate change and the school strike movement, which has inspired millions of young people to take action on climate issues.