Oxyopes castaneus is a species of spider in the family Oxyopidae. It is commonly known as Lawrence's lynx spider.
Oxyopes castaneus occurs in Namibia and South Africa. In South Africa, the species is known only from a single locality in KwaZulu-Natal at 42 m above sea level.
The species has been found on grasses within the Savanna biome. Due to the limited collection data, more sampling is needed to fully understand its ecological preferences and distribution range.
Oxyopes castaneus is known only from males.
Oxyopes castaneus is listed as Least Concern by the South African National Biodiversity Institute. Despite being known from only one sex and having a limited known range, the large distance between collection locations suggests the species may be under-collected. It is protected in Ndumo Game Reserve.