Gate Guardian

The Gate Guardians (aka Gatekeepers, Guardians of the Gates) are monstrous Underworld creatures whose task is to guard the five gates of the Underworld. Only four guardians are shown in the series, however, as the Zapotec city of Dani Baán was sunk underneath its gate by the God of the Underworld, Mictlantecuhtli.

Uxmal ("Jaws of the Jaguar")
The guardian of the first Underworld gate was a huge, multi-armed spider-like creature with a human skull for a mouth. It moved around on its eight spider-like legs and primarily attacked by swinging and grabbing rubble with its six arms. Like many creatures associated with the Underworld, it bled turquoise blood.

Lakamha ("The Stranger")
Unlike the other guardians, in which there only appears to be one at each gate, there were multiple crab-like guardians protecting the gate at Lakamha. They had the ability to spit hot water-like acid towards their target, which had the strength to unravel large ropes. They were also able to strengthen themselves into larger, more intimidating forms by consuming one another with tendril-like mouthparts.

Tajín ("What She Carries")
The guardian of the gate at Tajín was a Camazotz with enormous ears, able to pick up the slightest sound. It was able to maneuver in flight quite well, and was fast enough to keep pace with advanced flyers such as Manixna.

Old World Sentinel ("Death From Below")
The guardian of the gate underneath the Old World Sentinel statue was a bulky quadrupedal shark-like creature. It primarily moved around on four legs, but was able to rear up onto its hind legs in order to combat with enemies using its powerful front legs. It had a massive jaw with rows of sharp teeth. and a strong tail used for balance when standing on its rear limbs as well as for attacking. It was strong enough to put up a large fight against Zyanya's monstrous lizard form.

Trivia

 * The gate guardian of Tajín was heavily inspired by Camazotz, the bat god in Maya mythology. In the Popol Vuh, Camazotz are the bat-like monsters encountered by the Maya Hero Twins during their trials in Xibalba.
 * The gate guardian of the Old World Sentinel was possibly inspired by the Olmec "Shark Monster", thought to represent the Underworld.