Mankind has consumed or used, directly or indirectly, marine oils for thousands of years. There are indirect references to them in the Book of Tobit in the Bible. Hippocrates (460–370 BC) first recorded the medicinal use of fish oils, and Pliny the Elder in the first century (23–79 AD) recorded the use of dolphin liver oil as a remedy for chronic skin eruptions. The ancient Egyptians, Babylonians, Greeks, Assyrians, and many other cultures after them used animal liver as a treatment for night blindness. Assyrian medical texts (700 BC) thought night blindness could be cured by application of liver to the eyes. They used the extracted oil and ate the cooked liver. The Greeks shifted the recommendation from topical application to eating liver, soaked in honey. The choice of the animal was influenced by its availability in the community. Thus, we could assume that in maritime cultures, fish livers would also have been used as a remedy. The oils were consumed in Greece in the fourth and fifth centuries BC, and during the Roman period (27 BC–393 AD). Norway was recovering herring oil by primitive pressing during the Viking Period (800–1300 AD). Cod liver oil was used as a food by the Vikings as far back as (about 700–1100 AD). The marine oils category has now expanded beyond fish to include single-cell organisms and transgenic plants. This article will explore all these categories, some old, some very old, some new, and some very new.