Culverton Smith is a character in The Mary Morstan Mysteries series (as well as the original stories by Sir Arthur Conan Doyle) and was portrayed by Ray Frensham. He is a member of the Moriarty Club, and an expert on tropical disease and Arthropodology,Myriapodology and Entomology.
A creepy, eccentric and highly intellectual man, he is prone to speaking in Latin terminology regarding his studies, and mocking those that fail to decipher his meaning.
Smith appears in the episode "Rings of Change" (Series 2, Episode 1). In which he is a key figure to the construction of the super simian serum for Moriarty, providing him with the Langur adrenal gland extract, as well as assisting with the testing process. He further appears in "The Ecuador Equation" (Series 2, Episode 4) to present Moriarty with his final test report on the safety of the serum, and confirming it is ready for a black market release.
In the episode "Rings of Change". He presents Gwendolyn with the Mosquito encased in glass memento. This can later be seen over a century later in Gwendolyn's great-great-great-great-great granddaughter, Madeline Chambers house.