|Played By||Ron Selmour|
- "You're famous! Everyone knows you're that rich brat who took off with his friends on a yacht and partied his way into a shipwreck. And lucky for us, not all of you was shark bait. " – Marcos to Oliver Queen, Toxic
Marcos was Tess Mercer and Oliver Queen's abductor. He planned to ransom the two but they stopped him and wounded him. He returned for revenge many years later and poisoned Oliver Queen and his date, Adrianna. He attacked Tess Mercer, but was stopped by Clark Kent.
Oh. You don't think I know who you are? Oliver Queen?, Marcos to Oliver Queen, Toxic
Marcos and his gang killed a group of marine biologists studying the Pacific Ocean, kidnapping the survivors Tess Mercer and Megan. Marcos' gang also found a poisoned Oliver Queen and had Tess nurse him back to health so they could ransom him. Marcos shot Megan and prepared to leave on a boat. As he was leaving, Oliver shot Marcos with an arrow covered in poison of a flower that grew on the island. Oliver and Tess boarded the boat and left Marcos to die.
In 2008, Marcos returned for revenge, by poisoning Oliver Queen and his date. Marcos then left for the Daily Planet, slashing Tess Mercer's tires so she couldn't escape. He assaulted Tess but Clark Kent arrived and stopped him, knocking Marcos out. Marcos was arrested by the Metropolis police, but Tess Mercer paid his bail.
She then poisoned him with the same killer flower which he had used to poison Oliver. Tess told a taxi driver to take Marcos to the hospital, knowing they try to treat him by injecting him with adrenaline. He is presumably deceased.