Carlos is a character who makes a one-time appearance in the Season 3 episode titled "Wildfire".
Carlos is one of the drug pushers working with Alvin Brock, Noble Flowers and Moose to bring in drugs using Big Cece's oil refinery as a cover. When Little Cece was convinced by Dominic to refuse to deliver a shipment and thus expose his operation, Carlos and Alvin went after the Cece family. They caught up with them in a hotel but were overpowered by Dominic and Big Cece in a coordinated attack which they had developed during a bar fight when they were servicemen in Korea. Carlos and Alvin were knocked out and it is likely that Dominic and Big Cece would have tied them up for the authorities to pick up later.
Among the gang of pushers, Carlos appears to be the "muscle". He takes his instructions from Alvin. In most situations, Carlos leaves the talking to Alvin.