The Temple of the Skull
The Temple of the Skull is named for a skull carved at the base of the central pillar.
Maybe has link to Chan Bahlam
A rich tomb discovered beneath the Temple of the Skull in 1994 might be that of K’inich Kan Bahlam, although this is controversial (see David Stuart link below). On close inspection, the skull for which the temple is named can be seen in this photo at the bottom of the pier between the large rectangular doorway and the arch.
Skull from which the temple is named
The relief to which the Temple of the Skull owes it name is located at the foot of one of the pilasters on the facade. It probably represents a god of the underworld wearing ear ornaments in the shape of inverted ahau.
David Stuart has some fascinating speculation in his blog Maya Decipherment: Ideas on Ancient Maya Writing and Iconography where he pursues a link between the ruler Chan Bahlam and this temple. A wonderful read!