Athena is the Greek goddess of Wisdom. She is often depicted as a wise owl. The Romans know her as Minerva.
It's said that she wasn't born, but that she sprang from the head of her father, Zeus.
Athena is the patron of goddess of the City of Athens. The Parthenon Temple is dedicated to her. In ancient times it contained a giant wooden statue of the goddess that was covered in gold and precious gems.
She lost out in the beauty contest judged by the Trojan Prince Paris (he chose Aphrodite). Naturally, she suppors the Greeks in the Trojan war.
She is a big supporter of the Greek hero, Odysseus, who is know for his wily tricks. On his journey home from Troy, she helps him out numerous times. Sometimes she appears to him as his friend, Mentor (which is how we get the word "mentor" - meaning a person who advises you. ). She also helps Odysseus with his disguises, helping him to look like an old beggar when he returns home.
When the Greek hero Orestes was being chased by furies, he took refuge in her temple. Athena casts a vote to save his life and to persuade the furies to become kindly protectors of Athens. (See the Oresteia by Aeschylus)