Malcolm L. McCallum (born December 26, 1968[1]) is an American environmental scientist, conservationist, herpetologist, and natural historian and is known for his work on the Holocene Extinction.

He earned his BS with a double major in agriculture and biology from Illinois State University,[6][circular reference].

[13] In 1997 his discovery of deformed frogs in Madison County, Illinois[14] received media coverage in St. Louis news outlets.

He also organized and edited the First International Symposium on the conservation and sustainability of the ornamental fish industry on Rio Negro River, Manaus.

Many of his early papers were focused on natural history, but they also cover amphibian conservation, ecological immunology, and general biology.

[25] In 2019, he compared Google searches before and after release of the landmark encyclical, Laudato Si', revealing that interest in the environment rose markedly in most countries around the world.