This one was in the Upper Gascoyne River area, WA. I think it's Varanus gouldii. Last photo is the habitat - fairly flat scrubby country, along branches of the river which are more like small shallow seepages. Thanks.
it definitely is either a yellow spotted monitor, a sand/gould's monitor, or a perentie. i personally can't confirm which, though i think it's a yellow spotted's.
Thanks for the comments Imported_tuatara. I was tossing about with Goulds or Perentie. Never really considered panoptes. The spots on the underside seem to be banding up the sides, whereas the panoptes here never seemed to have that. Of course different area different story.
It is definitely a Yellow Spotted Monitor Varanus panoptes rubidus.
The continuation of the transverse rows of dark spots from the back onto the belly distinguished it from V. gouldii. It is not a Perentie as it has a black eye streak and lacks the black reticulum on the sides of the throat and neck.