Mark O’Shea MBE is an herpetologist with field experience on every continent except Antarctica, stretching back to the early 1980s. His specialist field is the snakes of New Guinea and Wallacea (including Timor-Leste), although he has considerable experience with Latin American, African and Asian herpetofaunas and has worked in more than 40 countries across six continents.

He was the herpetologist on the Royal Geographical Society "Maracá Rainforest Project" for seven months in the Territory of Roraima, northern Brazil during 1987-88, and a member of the Scientific Directing Staff for Operation Raleigh, Raleigh Executive and Discovery Expeditions, from 1985-1986 and 1989-1992.

He has more than four decades experience working with venomous snakes from all around the world, in captivity and in nature. He is a passionate advocate for reptile and amphibian conservation and a member of the Snake (formerly Boa & Python), Monitor Lizard and Skink Specialist Survival Groups of the IUCN (International Union for the Conservation of Nature).

He was first author on the descriptions of four new Papuan and Timorese snakes, and a co-author on the descriptions of seven other snakes and a gecko, from New Guinea, Timor, Java, and Borneo. Several other new snake species descriptions are in preparation. 

He has worked on a number of snakebite projects, in Papua New Guinea, Sri Lanka and Myanmar, as a specialist experienced with capturing and milking medically important venomous snakes, working with clinicians from the Universities of Oxford, Melbourne and Adelaide, and the Liverpool School of Tropical Medicine. He is on the WHO Roster of Snakebite Experts. He also has experience of snakebite from the victim's point of view.

He held the posts of first Curator of Reptiles, and then Consultant Curator of Reptiles, at West Midland Safari Park for a total of 33 years (1987-2019 inclusive) and accomplished first UK breedings for the endangered Aruba Island Rattlesnake (Crotalus unicolor) and Ornate Cantil (Agkistrodon taylori).

He has authored ten books, including A Book of Snakes: A life-size guide to six hundred species from around the world (2018, revised 2nd edition 2023), Lizards of the World (2021). Snakes of the World (2023), Frogs of the World (2024), The Book of Frogs (revised 2nd edition, 2025). Older titles include the A Guide to the Snakes of Papua New Guinea (1996), the DK Handbook to Reptiles and Amphibians (2000 now in 14 languages), Venomous Snakes of the World (2005) and Boas and Pythons of the World (2007). He is also working on a slow burn revision of his New Guinea snake book. He has contributed chapters to multi-author volumes, including snakes on Papuan islands, snakes of Wallacea, boids of the genus Candoia. Other book and chapter projects are on-going.

He has also presented around forty adventurous natural history documentaries for Discovery, Animal Planet, Channel 4, BBC & ITV, including his own international television series on Animal Planet for five years (1999-2003), known as "O'Shea's Big Adventure" (AP) or "O'Shea's Dangerous Reptiles" (Channel 4).

He is frequently invited to speak at conferences, symposia and herpetological meetings and he has presented his work orally or as a poster in the following countries: United Kingdom, Denmark, Sweden, Spain, Germany, Czech Republic, Slovakia, Serbia, South Africa, Sri Lanka, Indonesia, Australia, Papua New Guinea, United States, Mexico, Costa Rica, and Brazil.

He is a Fellow of the Royal Geographical Society, Linnean Society of London, Royal Society of Biology, and Explorers' Club of New York. He was awarded one of only eight Millennium Awards for Services to Exploration, by the British Chapter of the Explorers' Club in 2000 and an Honorary Doctor of Sciences degree, for services to herpetology, by the University of Wolverhampton in 2001. In 2015 Czech herpetologists voted him "Snakeman of the Year".

Mark O’Shea became Professor of Herpetology at the University of Wolverhampton in September 2018, the same year a new Asian pipesnake was described by German colleagues with the eponym Cylindrophis osheai, in his honour.

He is also a Scientitic Associate of the Natural History Museum in London.

He received an MBE (Member of the Most Excellent Order of the British Empire) in the Queen's Birthday Honours in October 2020 but the award ceremony was delayed because of Covid. The award was for services to Higher Education, Zoology, Reptile Conservation and Snakebite Research. He finally received the award from Princess Anne, the Princess Royal, at an investiture at Windsor Castle on 30 November 2021.

He completed a PhD by Published Works in 2025, the subject being "The Systematics, Biogeography, and Natural History of the Endemic Papuan Snake Genus Toxicocalamus (Elapidae: Hydrophiinae)".

In October 2021 he won an award for "Outstanding Contribution to Research" in the University of Wolverhampton Vice-Chancellor's 10th Staff Excellence Awards. In June 2023 he was awarded a "Lifetime Achievement Award" in the 2nd Annual University of Wolverhampton Alumni Association Awards.