Edit
Princess Athena is the player character in the 1986 SNK platform game Athena, also known as Athena's Wonder Land. She is supposed to be the Greek goddess Athena, and the whole game is themed on ancient mythology. The official name was originally just Athena, the title Princess was added over time and is maybe not official, but useful for a clearer distinction to her descendant Asamiya Athena.
Princess Athena has long purple hair held by a golden barrette. She wears a red bikini and purple sandals, wields a sword and a round brass shield with spikes.
Princess Athena made a second appearance in SNK vs. Capcom: SVC Chaos as a secret boss. Her costume was only slightly modified. She got a red fingerless glove on her shield hand, a heart-shaped shield with a lion's head, some additional ribbons, her sandals got wings and her barrette got decorations that look as if it was a tied ribbon. This version should be labeled SVC Chaos, the older one not.
In nude pictures, Princess Athena and Asamiya Athena can be distinguished by the barrette, which for the latter is usually red or white with a golden star, or (in KoF 2003) gold with a red heart. However, sometimes artists use one of Asamiya Athena's barrettes when they obviously intend to draw Princess Athena.
1