Hyastenus hilgendorfi is a species of spider crab from the family Epialtidae, classified in the sub-family Pisinae, from the Indo-Pacific region.

The merus of the pereopods also bear nodules, while the posterior border of the dactyl is spiny, the spines becoming successively larger distally.

[3] Hyastenus hilgendorfi occurs from the Red Sea through the Indian Ocean to the western Pacific to Hawaii and south to Australia.

[6] Hyastenus hilgendorfi is found on seabeds of coarse sand, debris and gravel, between 2 and 93 metres in depth.

[3] It is a "decorator crab" which uses other organisms to cover its body and in a study in the Suez Canal the barnacle Amphibalanus amphitrite, the tunicate Microcosmus sp., and the tube worm Hydroides elegans were found to be the most frequent epibionts.