Volunteer Feline Detectives (Panthera leo) were a pack of detective lions that once lived in the caves of the Mortmain Mountains.
The lions were once noble creatures trained by V.F.D. to detect smoke, and it is revealed in The Bad Beginning: Rare Edition that Beatrice and Bertrand Baudelaire once worked to train them. At some point, the fire-starting side of V.F.D. (including Count Olaf and his associates) took control of the felines.
The lions first appear in The Carnivorous Carnival. They were neglected and abused by Count Olaf who would whip them so hard their bodies have scars. The Baudelaires pitied them as they were lethargic and malnourished, one even having all its ribs visible. During their time at Caligari Carnival, the lions devour Olivia Caliban and The Bald Man with the Long Nose during the crowd chaos, but later perish when Count Olaf neglects to retrieve them from the lions' pit after setting fire to the Carnival. Lemony Snicket stated that he later found their blackened bodies.
The whereabouts of the remaining Volunteer Feline Detectives is currently unknown.
- In the film adaptation, a photograph of Aunt Josephine taming a lion is seen. As she was a V.F.D. member it is quite possible that the lion was from this pack.
- One of Gustav Sebald's films is called Lions in the Mountains.
- In the Netflix television adaptation of The Carnivorous Carnival, it is mentioned that the grounds near the Caligari Carnival are the haunt of starving members of the Volunteer Feline Detectives. Count Olaf captures two of the lions in an attempt to attract more spectators to the circus. As in the books, Esmé Squalor strikes a deal with the freaks to throw Madame Lulu to the starving lions. Count Olaf also attempts to feed "Beverly" and "Elliot" to the lions. Unlike the book, The Bald Man with the Long Nose is not killed. As in the book, the lions are mentioned to have been killed during the fire that destroyed the carnival.
- The Bad Beginning: Rare Edition (Mentioned only)
- The Carnivorous Carnival
- The Slippery Slope (Mentioned only)
- Lemony Snicket's A Series of Unfortunate Events (film) (Mentioned only)
- A Series of Unfortunate Events (TV series)