Pellucidar is the internal surface of a fictional Hollow Earth invented by American writer Edgar Rice Burroughs for a series of action adventure stories.

The stories initially involve the adventures of mining heir David Innes and his inventor friend Abner Perry after they use an "iron mole" to burrow 500 miles into the Earth's crust.

Also, several characters living in Pellucidar who are originally from the outer world appear to age slowly and exhibit considerable longevity.

The region in which Innes and Perry initially find themselves is ruled by the Mahars, a species of intelligent pterosaurs resembling Rhamphorhynchus with vast psychic powers.

Before their downfall, the Mahars used Sagoths (a race of gorilla-men who speak the same language as Tarzan's Mangani)[4] in enforcing their rule over any tribes who disobeyed their orders.

Technically, more advanced exceptions include the Korsars (corsairs), a maritime raiding society descended from surface-world Barbary pirates,[3] and the Xexots, an indigenous Bronze Age civilization.

The first novel was filmed as At the Earth's Core (1976), directed by Kevin Connor with Doug McClure as David Innes and Peter Cushing as Abner Perry.

Also, in the 1996 novelization of Tarzan: The Epic Adventures by R. A. Salvatore, based on the teleplay for the pilot of the series, Pellucidar is featured in the later part of the story.

None of the characteristics of it described in the novels are seen and the Mahars, Sagoths, Horibs, prehistoric mammals, stone age humans, and characters are not seen in this version of the inner world.

[13] The Hollow Earth milieu of Skartaris in the Warlord series of comic books by Mike Grell, published from 1976 to 1989, is essentially a translation of Pellucidar into the graphic medium, with the admixture of magic and elements of the Atlantis myth.

[15] The Hollow World of the fictional Dungeons & Dragons setting of Mystara shares many concepts from Pellucidar, such as the polar openings, the central sun, the floating moons, and the primitive cultures living in the internal surface.

In Robert A. Heinlein's Number of the Beast, the protagonists visit an inside-out world in their continua craft and discuss whether they have reached Pellucidar.

[citation needed] During the initial explorations of Lechuguilla Cave in the late 1980s, a chamber was named "Pellucidar" in honor of these stories.

[citation needed] The Hollow Earth concept was used by Vladimir Obruchev in his novel Plutonia, published in 1924, also inhabited by ancient life forms.