Guillermo Martínez, also known as José Guillermo Martínez, was a Venezuelan voice actor recognized for his work in Spanish-language dubs of anime series. Born on December 21, 1964, he passed away in November 2014.

His voice acting career included a variety of roles in productions dubbed in Latin American Spanish. Martínez is perhaps best known for his work in the anime series Fullmetal Alchemist: Brotherhood, where he provided voices for multiple characters including the Slicer Brothers, Heinkel, Fox, and a Shopkeeper. He also voiced the character Unicron in the series Transformers: Energon. In the Transformers franchise, his credits include the role of Demolishor in the Latin-American Spanish dub of Transformers: Armada. His career spanned various roles in the anime dubbing industry until his death in 2014.