Raymond Lee Ditmars (June 22, 1876 – May 12, 1942) was an American herpetologist, writer, public speaker and pioneering natural history filmmaker.

Ditmars left school at 16 with no formal qualifications but nevertheless gained a deep understanding of zoology through his own personal study of snakes and other animals in the wild and captivity.

In 1893, Ditmars was hired as an assistant in the department of entomology at the American Museum of Natural History, primarily because of his talent as an artist.

During the late 1920s, Ditmars helped bring about antivenom centers in the United States and Honduras, and soon after launched a series of expeditions to Central and South America in search of tropical specimens for the zoo.

His main quarry was a bushmaster, the world's largest type of viper, a specimen of which he successfully brought back from the island of Trinidad in 1934.

Many herpetologists of the baby boomer generation fell in love with reptiles in part through reading Ditmars's titles which, during the post-WW2 years, were often the only books on the topic available in school and town libraries.