
Elisa Aaltola is a Finnish philosopher, specialised in animal philosophy, moral psychology and environmental philosophy.

George Thorndike Angell was an American lawyer, philanthropist, and advocate for the humane treatment of animals.

Sir (Paul) Patrick (Gordon) Bateson, was an English biologist with interests in ethology and phenotypic plasticity. Bateson was a Professor at the University of Cambridge and served as president of the Zoological Society of London from 2004 to 2014.

Marc Bekoff is an American biologist, ethologist, behavioural ecologist and writer. He was a professor of Ecology and Evolutionary Biology at the University of Colorado, Boulder for 32 years. He cofounded the Jane Goodall Institute of Ethologists for the Ethical Treatment of Animals, and he is Professor Emeritus of Ecology and Evolutionary Biology at the University of Colorado, Boulder.

Ernest Bell was an English author, publisher and activist for animal rights and welfare, humanitarianism and vegetarianism.

Rev. Christa Blanke-Weckbach is a German Lutheran theologian and animal welfare activist. She is the founder of the European animal protection organisation Animals’ Angels. From 1995 to 1998 she chaired the animal welfare advisory board of the government of Hesse.

Gerald Hewes Carson was an American advertising executive, social historian and writer.

Stephen William Buchanan Coleridge was an English author, barrister, opponent of vivisection, and co-founder of the National Society for the Prevention of Cruelty to Children.

Christian Adam Dann was a German Lutheran pastor, theologian, animal welfare writer and supporter of Pietism.

Marian Stamp Dawkins is a British biologist and professor of ethology at the University of Oxford. Her research interests include vision in birds, animal signalling, behavioural synchrony, animal consciousness and animal welfare.

Joseph Morewood Dowsett F.R.G.S., F.Z.S. was an English big-game hunter, naturalist and writer. From the 1930s, Dowsett took interest in animal welfare.

Mary Tedeschi Eberstadt is an American essayist, novelist, and author of several books of nonfiction. Her writing has appeared in publications including Quillette, TIME, the Wall Street Journal, the Washington Post, National Review, First Things, The Weekly Standard, and other venues. In March 2017, she was named senior research fellow at the Faith & Reason Institute. Eberstadt spoke at the Edmund Burke Foundation's inaugural National Conservatism Conference in July, 2019.

Audrey Eyton was an English animal welfare campaigner, journalist and writer. She is best known for creating the F-Plan diet, a high-fibre diet that has been criticized as a fad diet.

George Fleming (1833–1901) was a Scottish veterinary surgeon and anti-vivisectionist. He was a prolific writer, and supported the passing of the Veterinary Surgeons Act 1881, which regulated the profession, in his time as President of the Royal College of Veterinary Surgeons.

Roger S. Fouts is a retired American primate researcher. He was co-founder and co-director of the Chimpanzee and Human Communication Institute (CHCI) in Washington, and a professor of psychology at the Central Washington University. He is best known for his role in teaching Washoe the chimpanzee to communicate using a set of signs taken from American sign language.

Ann Cottrell Free was an American journalist who wrote extensively on animal protection issues.

John Galsworthy was an English novelist and playwright. Notable works include The Forsyte Saga (1906–1921) and its sequels, A Modern Comedy and End of the Chapter. He won the Nobel Prize in Literature in 1932.

Mary Temple Grandin is an American scientist and animal behaviourist. She is a prominent proponent for the humane treatment of livestock for slaughter and the author of more than 60 scientific papers on animal behavior. Grandin is a consultant to the livestock industry, where she offers advice on animal behavior, and is also an autism spokesperson.

Stevan Robert Harnad is a Hungarian-born cognitive scientist based in Montréal, Canada.

Ruth Harrison was an English animal welfare activist and writer.

Rosalind Mary Theodosia Hill (1908–1997) was an English historian who for 39 years was a lecturer, Reader and Professor in History at Westfield College, a constituent college of the University of London.

Oscar Horta is a Spanish animal activist and moral philosopher who is currently a professor in the Department of Philosophy and Anthropology at the University of Santiago de Compostela (USC) and one of the co-founders of the organization Animal Ethics. He is known for his work in animal ethics, especially around the problem of wild animal suffering. He has also worked on the concept of speciesism and on the clarification of the arguments for the moral consideration of nonhuman animals.

Major Charles Westley Hume OBE MC BSc was a British animal welfare activist and writer.

Jane Louise Hurst is the William Prescott Professor of Animal Science at the University of Liverpool. She is Head of Mammalian Behaviour & Evolution. She studies scent communication between mammals, as well as animal welfare and pest control. She served as the President of the Association for the Study of Animal Behaviour from 2010 to 2012.

Thomas Jackson, was an English Anglican clergyman appointed in 1850 as Bishop Designate of the newly founded settlement of Lyttelton in New Zealand. After disagreements with the New Zealand colonists, Jackson never took up the bishopric, and instead returned to England. He was an early advocate of animal welfare.

Albert Knapp was a German poet and animal welfare activist.

Andrew Linzey is an English Anglican priest, theologian, and prominent figure in Christian vegetarianism. He is a member of the Faculty of Theology at the University of Oxford, and held the world's first academic post in Ethics, Theology and Animal Welfare, the Bede Jarret Senior Research Fellowship at Blackfriars Hall.

Francis Orpen Morris was an Irish clergyman, notable as "parson-naturalist" and as the author of many children's books and books on natural history and heritage buildings. He was a pioneer of the movement to protect birds from the plume trade and was a co-founder of the Plumage League. He died on 10 February 1893 and was buried at Nunburnholme, East Riding of Yorkshire, England.

Ingrid Elizabeth Newkirk is a British-American animal activist and the president of People for the Ethical Treatment of Animals (PETA), the world's largest animal rights organization. She is the author of several books, including The PETA Practical Guide to Animal Rights: Simple Acts of Kindness to Help Animals in Trouble (2009) and Animalkind: Remarkable Discoveries About Animals and Revolutionary New Ways to Show Them Compassion (2020). Newkirk has worked for the animal-protection movement since 1972. Under her leadership in the 1970s as the District of Columbia's first female poundmaster, legislation was passed to create the first spay/neuter clinic in Washington, D.C., as well as an adoption program and the public funding of veterinary services, leading her to be among those chosen in 1980 as Washingtonians of the Year. She is an atheist.

George Nicholson was an English printer, author, and vegetarianism advocate.

David Pearce is a British transhumanist. He is a prominent figure within the transhumanism movement and is one of the co-founders of the World Transhumanist Association, currently rebranded and incorporated as Humanity+. He approaches ethical issues from a lexical negative utilitarian perspective.

Maude Gillette Phillips was an American author and educator. She was the author of Popular Manual of English Literature. Phillips was a prolific writer for magazines in fiction and criticisms under pen names. Known for her wide social experience, she seemed to be more a woman of the world than a scholar or author.

Rodney John Charles Preece was a British-Canadian political philosopher and historian of animal rights and vegetarianism. He was professor emeritus in the Department of Political Science at Wilfrid Laurier University. Preece authored and edited 19 books on topics including animal rights and welfare, vegetarianism, German politics, socialization in Europe, and political theory.

Francis Harold Rowley was an American Baptist minister, animal welfare campaigner and hymn writer.
Boria Sax is an American author and lecturer and a teacher at Mercy College.

Christopher M. Sherwin was an English veterinary scientist and senior research fellow at the University of Bristol Veterinary School in Lower Langford, Somerset. He specialised in applied ethology, the study of the behaviour of animals in the context of their interactions with humans, and of how to balance the animals' needs with the demands placed on them by humans.

Peter Albert David Singer is an Australian moral philosopher, currently the Ira W. DeCamp Professor of Bioethics at Princeton University. He specialises in applied ethics and approaches ethical issues from a secular, utilitarian perspective. He is known in particular for his book Animal Liberation (1975), in which he argues in favour of veganism, and his essay "Famine, Affluence, and Morality", in which he argues in favour of donating to help the global poor. For most of his career, he was a preference utilitarian, but he stated in The Point of View of the Universe (2014), coauthored with Katarzyna de Lazari-Radek, that he had become a hedonistic utilitarian.

Laurids Smith, also known as Lauritz Smith was a Danish clergyman, philosopher and early animal rights writer. He was Scandinavia's first known advocate of humane treatment of animals.

Thomas Bywater Smithies was an English radical publisher and campaigner for temperance and animal welfare. He was the founder and editor of The British Workman.

William Olin Stillman was an American physician, animal welfare activist, humanitarian and medical writer.

Charles Bell Taylor was an English ophthalmic surgeon, known also as a campaigner against the Contagious Diseases Act and vivisection.

Michael Charles Tobias is an American author, environmentalist, mountaineer, and filmmaker. In 1991, Tobias produced a ten-hour dramatic television series, Voice of the Planet, for Turner Broadcasting; the series starred William Shatner. Tobias has written numerous books, most notably World War III: Population and the Biosphere at the End of the Millennium.

Ernst von Weber was a German travel writer, advocate of German colonization, animal welfare campaigner and opponent of vivisection.

Jon Linden Wynne-Tyson was an English author, publisher, Quaker, activist and pacifist, who founded Centaur Press in 1954. He ran Centaur Press from his home in Sussex and was a distinguished independent publisher. He authored books on animal rights and vegetarianism. At one time Wynne-Tyson held the title of "King of Redonda", a literary title referencing a small island.

William Youatt was an English veterinary surgeon and animal welfare writer.