Otto Lidenbrock is the uncle of the narrator, Axel, and a central character in the novel. He is a professor of "chemistry, geology, mineralogy, and many other ologies" who has invited his nephew to live with him and study in Germany. He is the catalyst who sets the plot into motion.

The somewhat eccentric Lidenbrock (who, in some editions, is renamed Hardwigg) is fixated on his studies and is a man of great enthusiasm who thinks nothing of hurtling into danger in the pursuit of knowledge. Thus, when Lidenbrock finds a coded message in an Icelandic document he has purchased, his nephew, who translates it, at first doesn't want to tell him what it says. When he does tell him that it is about journeying to the center of the earth, Lidenbrock, as Axel fears, jumps headlong into the adventure of going down an Icelandic volcano to the earth's mysterious depths.

Lidenbrock provides the science and the color in the novel. He is endlessly curious and fearless, able to plan their journey, and able to understand and explain what they see as they travel. Because of his optimistic, energetic, and unstoppable personality, he doesn't take his nephew's fears seriously and insists they plunge deeper into the earth. In response to his insistence, the explorers see things they might otherwise not have witnessed but also have some brushes with serious danger. The professor, however, is unafraid of death and able to speak of it dispassionately as they are being whirled upward to the surface of the earth by a volcanic eruption.