Two ships of the Royal Fleet Auxiliary (RFA) have borne the name RFA Olynthus:
- RFA Olynthus was an oiler launched in 1918 as and was in service with the RFA from March 1918 through to 1949. She was renamed Olynthus in 1937.
- was a fast fleet tanker launched in 1964, the lead ship of her class. She was renamed Olwen in 1967 to avoid confusion with the , .