Odiellus spinosus is a species of harvestmen in the family Phalangiidae.

Odiellus spinosus can reach a body length of 6.5 - 8 mm in males, of 7 - 11 mm in females. This harvestmen shows three large, almost flat spines (hence the species name) in front of the eyes and a black-edged saddle on the back. Moreover the abdomen is distinctly flattened, with some rows of brown spots across each tergite.

Adults can be found from June and until December.