Pseudotyrannochthonius giganteus is a species of pseudoscorpion in the Pseudotyrannochthoniidae family.

[1] The species occurs in south-west Western Australia.

The type locality is Calgardup Cave, near Augusta in the Leeuwin-Naturaliste National Park.

The type specimens were collected from the final chamber on roots hanging from the cave ceiling.

[1][2] The pseudoscorpions are cave-dwelling, terrestrial predators.