Although Peter Dinklage stars as Winston Gooze and provides the voice for the mutated protagonist, the physical performance of the Toxic Avenger is portrayed by Luisa Guerreiro. To ensure the character's movements remained consistent with Dinklage's acting style, the production utilized a specialized "mirroring" process. Dinklage first filmed a complete version of the movie in a plain room, performing every scene as Toxie to establish the character's gait, timing, and physical choices. Guerreiro, a movement artist and creature performer whose credits include "Teletubbies" and "Wicked", then studied this footage to replicate Dinklage's performance on set while wearing 30 pounds of foam prosthetics. Dinklage returned six months later to record the final voice track, timing his dialogue to match Guerreiro's physical delivery.
