Who Is Medusa And What Is Her Importance In Greek Mythology?

Medusa was one of the three Gorgons known as The Grim Ones.

Medusa the Ruler
Euryale the Wanderer
and Sthenno the Strong One

One glance from a Gorgon can turn a person to stone as u already know.

Two of the sisters were immortal but Medusa was mortal and she was killed by Perseus. He used her reflection in his shield to guide his hand and cut off her head. When drops of her blood fell into the sea, they became scarlet coral branches, still known as Gorgonia.

Also she has a connection to Atlas because Atlas was the leader of the Titans and during the great war between the gods and Titans, Atlas stormed the gods' stronghold of mount Olympus. When the gods eventually won, the Titans were banished, except Atlas who was sentenced to carry the skies on his shoulders forever. When Perseus flew past him, carrying Medusa's head Atlas was turned to stone. Hope this helps.