Tyrannochthonius garthhumphreysi is a species of pseudoscorpion in the Chthoniidae family. It is endemic to Australia. It was described in 2008 by Australian arachnologists Karen Edward and Mark Harvey.
The species occurs in North West Australia. The type locality is a borehole in limestone karst, 7 km north of the Chevron Texaco camp, on Barrow Island off the Pilbara coast.
The arachnids are cave-dwelling, terrestrial predators.