Tarzan and the Leopard Men might not have been Edgar Rice Burroughs’ best Tarzan novel. In fact, it might have been his worst. Richard A. Lupoff said in Edgar Rice Burroughs: Master of Adventure (1975) when speaking of Tarzan and the Forbidden City: “Next to Tarzan and the Leopard Men this is probably the worst of the Tarzan books.” That aside, it does have one feature that no other Tarzan novel has, an actual African group, the Leopard Society. Most details in ERB’s Africa are entirely fictional. As a historical document, it is pretty far-fetched or inaccurate. (We don’t usually care because ERB filled it with fantastic and amazing details of his own invention.) But the Leopard Men are different.
For one thing, they actually existed. The earliest reference to the cult was in George Banbury’s Sierra Leone: or the white man’s grave (1888). The West African secret society was known for wearing leopard skin and using a claw-like weapon to simulate a leopard attack. Some believed they were were-creatures who became leopards.
Burroughs’ eighteenth Tarzan novel was serialized in The Blue Book (August September October November December 1932–January 1933) with illustrations by Frank Hoban.
The idea was popular among Pulpster besides Burroughs, like Edmond Hamilton, who used it for “The Leopard’s Paw” (Popular Detective, March 1936).
The comic books were not slow to use the cult of the Leopard Men either. Since it really existed it did not belong to the copyright of one company. Not surprising, jungle-themed comics were the most frequent to use the material. The Leopard Society faced off against Sheena, Ted Crane, The Hurricane Kids, Nyoka, Jack Armstrong, Charlie Chan, Tiger Girl, Lee Granger, Taanda, Tarzan, of course, Korak and the Brothers of the Spear, Dan-el and Natongo. Several comics used the Leopard Men for a single-pager to thrill readers.
Most of the authors of these stories are unknown. They are indicated where possible. Most of these older comics can be downloaded for free at DCM.
“Drums of the Leopard Men” (Jungle Comics #1, January 1940) has Buck Barton thwart a plot to use the Leopard Men to steal diamonds.
“Ted Crane and the Leopard Men” (Exciting Comics #2, May 1940) fights Leopard Men on his ship and on the land. And not all the Leopard Men prove to be African!
“The Queen of the Elephants” (Master Comics #7, October 1940) was probably written by Manly Wade Wellman. Lee Granger looked like Tarzan but thought like a physics professor. Read more about the series here.
“The Hurricane Kids” (Popular Comics #68, October 1941) was written by Albert Hartje. Dave and Allan face off against the evil that has been killing locals. They have to cut their way to freedom. This comic was surprising for its violence.
“Leopard Men” (Sheena, Queen of the Jungle #1, Spring 1942) was a one-page filler.
“Claws of Spotted Terror” (Sheena, Queen of the Jungle #2, Winter 1942) was written by W. Morgan Thomas (a house name. Wil Eisner and Jerry Iger used pseudonyms to make their small outfit look bigger.) Sheena was the first female lead character in comics. She beat Wonder Woman by several years. Based on Rima from Green Mansions (1904) by William Henry Hudson, she was a female Tarzan. As the headliner for Jumbo Comics, she appeared on most covers. It took two years for the Leopard Men to show up in a story but they finally did.
“The Human Leopards” (Nyoka the Jungle Girl #13, November 1947) was written by an unknown author. Nyoka got her start in the serial, Edgar Rice Burroughs’ Jungle Girl starring Frances Gifford in 1941. It was followed by The Perils of Nyoka and Nyoka and the Tigermen (both 1942) starring Kay Aldridge. The ERB connection is the first serial was based on his Land of the Hidden Men, set in Cambodia. The comics proved popular and appeared at three different publishers: Fawcett (1945-1953), Charlton (1955-1957) and AC (1988-2005). That’s amazing longevity for a character that was no longer in Hollywood by 1943.
“Land of the Leopard Men” (Jack Armstrong #4, February 1948) is based on a Radio character, Jack Armstrong, All-American Boy. Jack received a Big Little Book in 1937, Jack Armstrong and the Ivory Treasure (1937) based on a script by Talbot Mundy, the famous adventure writer. The character got a comic book from Parents’ Magazine Press for thirteen issues, when Jack got a serial. This fourth issue finally delivered Leopard Men.
“Land of the Leopard Men” (Charlie Chan #1, June-July 1948) features the Asian detective, Charlie Chan. Chan was a creation of Earl Derr Biggers, who wrote six novels starting with The House Without a Key (1925). Chan was played famously by Warner Oland though several others played him as well in films. Charlie had Radio, television and stage shows, games and, of course, comic books and newspaper comic strips. The second comic book was published by Prize Comics, the first having the Leopard Men. (The first was Big Shot that reprinted the comic strip.)
“Kraal of Evil Ivory” (Jumbo Comics #121, March 1949) saw the return of the Leopard Men, seven years later. Sheena saves some white men from the spotted fiends, only to have to stop the whites from enslaving a village. 
“Judy and the Leopard Men” (Exciting Comics #67, May 1949) was written by Charles S. Strong, who penned numerous comic text stories. He later wrote Hardy Boys and Nancy Drew books. Judy was one of a number of Jungle Girls to appear in different comics.
“Tarzan and the Leopard Men” (United Features comic strip) appeared August 15, 1949 and November 12, 1949. It was adapted by Paul Reinman.
“Beware the Congo Cobra” (Fight Comics #65, December 1949) was written by Allan O’Hara. Tiger Girl saves some white men from the Akbha, the Leopard Men, only to have to stop the whites from enslaving a village. (Hey, that sounds familiar!)
“Strange Legends” (Witches Tales #1, January 1951) was written by an unknown author.
“The Leopard Men” (Strange Worlds #2, April 1951) had this one-pager on the inside cover of their second issue.
“The Leopard Men” (Stamps Comics #1, October 1951) tells how the French captured the dreaded Leopard Men.
“The Leopard Men!” (White Princess of the Jungle #3, May 1952) features Taanda, another Jungle girl, in a text story. I’m not sure why Avon felt they had to add that “White” in the title. Almost all of the jungle girls were white. (Voodah was an exception.)
“Leopard Men” (Jungle Comics #155, November 1952) is an unusual piece for a comic devoted to jungle stories. After Sheena’s success at Jumbo Comics, Fiction House created Jungle Comics for a slew of other characters, mostly Kaanga. With Kaanga, Wambi the Jungle Boy, White Panther, Tabu, Wizard of the Jungle, Camilla, the Red Panther, etc., why do the Leopard Men appear in a one-shot? “Mysteries of the Jungle” was a regular comic with different characters each month. This may be the only comic where the Leopard Man is actually a were-leopard.
“Tarzan on the Trail of the Leopard Men” (Edgar Rice Burroughs’ Tarzan #40, January 1953) was written by Gaylord DuBois. It is surprising that a proper adaptation of Tarzan and the Leopard Men did not appear at Dell or later at Gold Key or even DC for they did most of the ERB novels. Perhaps they felt it was too familiar because of the comic strip from 1949. This back-up story did appear in 1953 but it is not an adaptation.
“The Leopard Men” (Tomb of Terror #9, May 1953) is another one-pager from a Horror comic.
“Trapped by the Leopard Men” (Boys’ and Girls’ March of Comics #354, February 1971) was written by Gaylord DuBois and drawn by Dan Speigle.
“Tree of Mystery” (Brothers of the Spear #13, April 1975) was written by Gaylord DuBois. Despite the cover, the Leopard Men are only in the first two pages of a story about other people altogether. The Leopard Men get the heroes and villains together by attacking.
“Spotted Death” (Ghostly Tales #123, October 1976) was written by Joe Gill.
“Night of the Leopard Men!” (Tarzan Weekly #1, June 11, 1977) was written by Mark Evanier. Korak meets the Leopard Men.
Conclusion
The Tarzan films haven’t ignored the Leopard Society either. Tarzan and the Great River (1967) moved the action to South America, changing the Leopard Society to the Jaguar cult. (I can remember being thrilled when Mike Henry showed the audience the wicked jaguar claw club.) The Legend of Tarzan (2016) does a good job of working the Leopard Men of Opar into the story of the death of Kala, Tarzan’s ape mother. Djimon Hounsou as Chief Mbonga steals the show at times, with a villain you can understand, rather than just hate. (Fans know that Opar has a different story entirely, but it all worked nicely in the film.) The movie uses more historical touch points than most of ERB’s work, a necessity in the 21st Century.