The Calaveras are a family of Hunters who have their headquarters in Mexico but have occasionally crossed the border to america to recruit Chris Argent. Unlike the Argents such as Chris and Allison, the Calaveras are more ruthless and seem to enforce the rule of suicide for a hunter who has been bitten by an Alpha. They also have no qualms about torturing others, even teenagers.
The Calaveras are more brutal than the argents as their leader Araya Calavera, killed one of her own men simply for stealing from her. However, they do seem to possess a code, as they warn Scott that they won't bother him unless he bites an Innocent.
For the majority of their appearances, they were obsessed with tracking down the "She-Wolf", who was later revealed to be Kate Argent, a hunter who was turned by Peter Hale when he had slashed her throat.