Lebia Mavelick is a Visionaire, a person whose cybernetic implants allows her to directly interface with computers. She is a special Alpha-class Visionaire whose databank is in an orbiting satellite named Donald, giving her a memory capacity 3000 times that of an ordinary Visionaire. She created the Artificial Intelligences Huey, Dewey, and Louie. While the obvious reference is to Donald Duck's nephews, it is likely that the naming came as a familiarity with (or homage to) the film Silent Running, where the three robot drones are given the same names. Louie resembles the monolith from the classic film and Arthur C. Clarke novel 2001: A Space Odyssey; Dewey is a vaguely humanoid walking robot; and Huey is a motorcycle.

As second-in-command of the AMP, Lebia often has to deal with paperwork and disciplining Katsumi and Kiddy. As a Visionaire, Lebia has a deep affinity for machines and can be very emotional when one she was close to gets destroyed. She is the pilot of the Simurgh, the AMP's mobile command center and attack craft.

Lebia's grandfather was Stefan Mavelick, who created the first Visionaires. He also built the Cyclotron, a massive circular device buried under Tokyo that was central to Project Gaia.

In Silent Mobius QD Lebia has assumed Rally's role as chief of AMP, though still maintains her Visionaire abilities. She now appears to have the form of a young girl with limited physical movement.