There are many different names for the gods of the Celtic pantheon. These names have either been recorded by Ancient Greek or Ancient Roman geographers, or they have been found in inscriptions on graves. Among the most prominent of these gods are Teutatis, Taranis and Lugus. People involved in comparative mythology have also added figures from medieval Irish mythology to this list. They say that these figures are deities or heroes from earlier times that have been interpreted in a different way. This process is known as "Euhemerisation", after Euhemeros, a philosopher from Ancient Greece who described this process. 