Medusa was originally a beautiful maiden, a virgin priestess of Athena. She was the aspiration of many suitors and of all her beauties none was more admired than her hair; she even boasted that she was prettier than Athena herself. Her incredible beauty attracted even the attention of the god Poseidon. Delighted by that, she let Poseidon into Athena's temple and slept with him on the altar.
Athena was understandably enraged that her priestess not only broke her vows but did it in her temple, so she punished her by taking away what she was most proud of: She transformed Medusa's beautiful hair to serpents and cursed her so that everyone who gazed upon her face would turn to stone. So she was forced to flee to a desolate island where she lived as a famed monster. Many brave warriors set out to slay her, ending up as sculptural decoration of her abode, until the hero Perseus (with the help of Athena, among others) finally killed her.
So this is my take on Medusa from the Greek mythology, lonely and grieving her curse, approaching more in sorrow than in anger a man who has just met his fate because he tried to slay her
I think it is a moving story and even if her punishment was deserved (in some versions she didn't even do the nasty thing willingly, but was raped by Poseidon), I see her as a tragic character rather than a villain.
In fact there are many versions of the myth. And the evolution of it is quite interesting: From what I have read, apparently in the oldest version she was just a dreadful primeval chthonic monster with tusks and brazen claws and a face so terrible to behold that the mere sight of it would turn onlookers to stone. But this later evolved to her being originally a beautiful maiden turned as a punishment into a terrible ugly monster and even later she was seen (e.g. in some depictions) as being still beautiful as well as terrifying
– cursed by the mere fact that nobody can behold her and live (well, this and the snakes for hair🐍). But then the modern popular culture has apparently reversed that trend, making medusa into a stock monster in films, games, comics etc., the more ugly and terrifying, the better.
Anyway, in the version of the story I prefer, I think having hair turned into serpents is just enough; no need to make her any uglier. This way I think the tragedy of her story is more emphasized.
By the way, I wonder, whence did the popular notion of Medusa having snake tail come? I mean, I like such fantastical half-human creatures (such as centaurs, mermaids and nagas), but in this case I think it is not really necessary. I suspect the Clash of the Titans film might have played a role in it.
And what do you think of Medusa? Do you prefer her being an evil monster or a tragic character?