The setting for The Lost World is believed to have been inspired by reports of Doyle's good friend Percy Harrison Fawcett's expedition to Huanchaca Plateau in Noel Kempff Mercado National Park, Bolivia. Fawcett organized several expeditions to delimit the border between Bolivia and Brazil - an area of potential conflict between both countries. Doyle took part in the lecture of Fawcett in Royal Geographic Society on 13 February 1911 and was impressed by the tale about the remote "province of Caupolican" (present day Huanchaca Plateau) in Bolivia - a dangerous area with impenetrable forests, where Fawcett saw "monstrous tracks of unknown origin".

Edward Malone, the narrator of The Lost World, the novel in which Challenger first appeared, described his first meeting with the character:

His appearance made me gasp. I was prepared for something strange, but not for so overpowering a personality as this. It was his size, which took one's breath away - his size and his imposing presence. His head was enormous, the largest I have ever seen upon a human being. I am sure that his top hat, had I ventured to don it, would have slipped over me entirely and rested on my shoulders. He had the face and beard, which I associate with an Assyrian bull; the former florid, the latter so black as almost to have a suspicion of blue, spade-shaped and rippling down over his chest. The hair was peculiar, plastered down in front in a long, curving wisp over his massive forehead. The eyes were blue-grey under great black tufts, very clear, very critical, and very masterful. A huge spread of shoulders and a chest like a barrel were the other parts of him which appeared above the table, save for two enormous hands covered with long black hair. This and a bellowing, roaring, rumbling voice made up my first impression of the notorious Professor Challenger.