Marcos Eringrad Garcia, often referred to as Marcos E. Garcia, is a character from the anime Terra Formars: Revenge. He is a sixteen-year-old boy from the cartel-dominated northern region of Gran Mexico. He lived with his mother for most of his childhood and knew very little about his father beyond the fact that he was a gangster. At the age of six, he met Alex Kandley Stewart at his mother's former workplace, and the two became close friends. Marcos has held many part-time jobs over the years, but he typically starts skipping work a few days or even minutes after payday. Motivated by a desire to escape poverty and find honest work, he joined Alex's plan to enter the Annex Project, hoping to obtain American citizenship in the process. Along with Alex and another childhood friend, Sheila Levitt, Marcos signed up for the genetic modification program that would send them to Mars. His Mars ranking is number nine.

In terms of personality, Marcos is spirited and somewhat impulsive. He has a laid-back attitude toward responsibility, as indicated by his habit of abandoning jobs shortly after receiving payment. Despite this, he is fiercely loyal to his friends and willing to take on the dangerous mission for a chance at a better life. His favorite food is fried chicken, and his hobby is playing the guitar. He dislikes customers who order tobacco under an alias, a detail that reflects some of his past work experiences.

Marcos undergoes the surgical genetic modification based on the brown huntsman spider, Heteropoda Venatoria. When he activates the transformation serum, he gains the attributes of that spider scaled up to human size. This grants him extraordinary strength, ferocity, and incredible speed that can surpass even the Terraformars, leaving them no time to counterattack. His speed is sufficient to dodge and even catch bullets. He also possesses high endurance, allowing him to fight without rest until the serum's effects wear off. In battle, Marcos wields a staff he calls the Archnebuster Mk.II, which he uses to deflect ranged attacks and impale the humanoid cockroaches. His friends mock the name, pointing out that it sounds as if the weapon is meant to bust spiders rather than roaches.

In the story, Marcos is a supporting member of the Annex I team during the Terra Formars: Revenge arc. He fights alongside his friends and other genetically enhanced soldiers against the mutated cockroaches on Mars. His key relationships are with Alex Kandley Stewart, his childhood friend and fellow soldier, and Sheila Levitt, another close companion from his past. Over the course of the series, Marcos's role involves using his speed and agility in combat, often working in coordination with his team. While the available information does not detail a major personal arc of transformation, his background and motivations establish him as a character driven by the hope of leaving poverty behind and securing a stable future. His abilities make him a valuable asset on the battlefield, and his camaraderie with his friends underscores a sense of loyalty and shared purpose.