Yaldabaoth, the self-proclaimed god of all monsters, is Dirk Strider's denizen in the Land of Tombs and Krypton, who shares a name with Dirk's browser of choice. He is also Caliborn's denizen, appearing in Earth's core after Caliborn brought Earth into his session. It has also been implied, but not confirmed, that Calliope was also assigned Yaldabaoth in an alternate timeline where she played instead of Caliborn. Yaldabaoth is the rarest, most powerful, and most inhospitable of the denizens, and is "usually designated for the most naturally gifted warriors". Additionally, it is implied that (due to his extreme nature and difficultly) he is always assigned in dead sessions. According to Aranea, he is "notoriously inhospitable" and is known for offering extreme Choices.
Yaldabaoth is a demiurge in the Gnostic school of philosophy that is a being who created and maintains the physical universe. Gnosticism requires a demiurge because it postulates that God, being perfect, could not create the imperfect world that humans inhabit. Yaldabaoth is the creator of man, and is depicted as having the face of a lion and the body of a serpent, and he is also associated with fire. He is described as being half-flame and half-darkness.
Dirk's chumhandle "timaeusTestified" references the concept of the demiurge, as it was first put forth by Plato in his dialogue Timaeus. However, the concept of Yaldabaoth is by nature from an offshoot of Christianity, making it an oddity amongst six of the seven other Denizens (excluding Abraxas, Jake's Denizen) who are named after classical Greek mythological figures.
A statue or minion of Yaldabaoth, comparable to the Typheus minion in Jade's house, was seen in the Act 6 Act 4 Flash on the Land of Tombs and Krypton. He was later seen in person when Caliborn talked to his Denizen, making him the first Denizen to appear on screen in the comic. He has the body of a giant red serpent and his head is either obscured by or made of a bright light comparable to that of a sun.
In Act 6 Intermission 4, it was revealed that Yaldabaoth appeared in the core of Earth when the planet entered the Medium, becoming its Denizen. It is also mentioned that Yaldabaoth is capable of "unlocking" Caliborn's true land. Later it was revealed that this meant bringing the dead Earth back to life after a long process of conquering and destroying several planets. Earth at this point is seemingly renamed, although the exact name is currently unknown, being obscured in similar fashion to a previous planet.
In Act 6 Intermission 5 Yaldabaoth's door is surrounded by various carvings. Above it are a pair of sillhouettes similar in appearance to Echidna and a number of Time gears (because Caliborn is a Time Player). Even more curious is the shape of the carving around the door itself, which is the silhouette of Doc Scratch's grandfather clock. Furthermore, the pillars to the left and right of the door feature the same imagery as the lower half of the grandfather clock. Aranea explains that Yaldabaoth gave Caliborn The Choice, this is the choice to take the path of a passive or an active player, and of course Caliborn chooses the latter.
The colors associated with Yaldabaoth are similar to Dirk's chat color and the red that Lil Hal uses in order to differentiate between himself and his creator.
Aranea mentions in Act 6 Intermission 5 that Yaldabaoth spoke to Caliborn in a language that only his player could understand. It is unclear whether this is specific to Yaldabaoth, or common to all denizens, and- if it is the former- whether it is used for all the players he is assigned, or only for those in dead sessions.Second from left.
The entrance to Yaldabaoth's lair resembles Doc Scratch's grandfather clock and the rooks in Calliope and Caliborn's Chess set. The pillars around it seem to depict cherubs in their mating form.
The path to the "treasure" Vriska speaks of happens to have a walkway shaped like Yaldabaoth.