The Mayans Motorcycle Club is a motorcycle gang that controls parts of California and all of Nevada. The President of their Oakland chapter is Marcus Álvarez, who is also the club's National President. All of the members of the Mayans seem to be Hispanic, most likely Mexican. Their insignia is a Mayan tribal symbol and their cuts bear the phrase "Los Asesinos de Dios" which in English means Assassins of God. The gang's main business is the heroin trade and they are also involved in prostitution.

At the beginning of Season One, they stole the Sons of Anarchy's guns from their weapon storage and burned down the warehouse, prompting a turf war over the right to rule the San Joaquin Valley. They planned to use these guns to hijack a One-Niners heroin shipment. However, the Sons of Anarchy located the guns in an industrial storage warehouse in San Leandro and retaliated by stealing the guns back and destroying the building, as well as killing three Mayans members in the process. The Mayans then allied themselves with the Nordics in an attempt to break the Sons of Anarchy's iron-fisted and tyrannical control over the town of Charming, as the SOA supply their competition with weapons. They also provided muscle for the Nords' drug pushing in exchange for 20% of the profit. The affiliation was ended, however, when they tried to kill Nord leader Ernest Darby. The Mayans and SOA eventually made a deal in order to stop a war; every SOA-Mayan dispute club-wide would end in the Sons' favor, and the SOA will begin selling the Mayans weapons. However, when both gangs met in Oakland to make a deal, the One-Niners attacked and killed a number of Mayans.

In Season Two, the Mayans aligned themselves with the League of American Nationalists. LOAN provided guns to the Mayans free of charge in exchange for a cut of the Mayans' prison heroin trade. Álvarez also used his new strength to declare war on all members of the Sons of Anarchy everywhere and receiving push in on One-Niner and Triad turf. In the season finale, LOAN leader Ethan Zobelle was run out of town by SAMCRO. They could not kill him, however, as he stalled for time by using a school group as cover while they were stopped at convenience store. He was eventually spared when the Sons pursuing him pulled off due to the news of Abel's kidnapping.

In Season Three, the Mayans have a low-level MC, the Calveras, provide protection for a drug shipment in exchange for being patched in to the Mayans. They also however execute a drive-by at SAMCRO prospect Half-Sack's wake. The Sons confront Calveras president Hector Salazar over this and he reveals the Mayan drug shipment. They then easily steal the drugs and convince the Mayans to use Lodi MC, The Grim Bastards as muscle. Enraged, Salazar kills a member of the Grim Bastards and is kicked out of his club by Alvarez.

Season Four shows the Sons and Mayans are still allied and are stated to have provided protection for them in prison. Alvarez later introduces Clay and Jax to Romero Parada AKA Romeo of the Jose Galindo Cartel. The two MC's then work together to transport and stash their cocaine for them in exchange for large amounts of money.