I love this question a bit too much. I think I have a good few.
1. The myth of Perseus and Medusa. He's one of the few heroes that gets.. as happy of an ending as you can. The idea of being born, protecting your family, slaying a legendary beast, and getting a hot wife out of it is pretty awesome. I'd so recommend reading about it because this isn't the myth I want to focus on explaining.
2. The myth of Atalanta. She was, ignoring the UNHAPPY(ish) ending, one of the coolest women arguably in greek mythology. Raised by bears, abandoned by her royal father until it became clear she was too badass to leave out there being a warrior in the wild. She was forced to find a way of getting suitors to compete for her, and chose for them to race her. They got a head start, but if they surpassed her, she killed them.
A lot of men died, until eventually one guy named Hipposomething(I think) enlisted the help of Aphrodite because he loved Atalanta past her riches and royalty and looks.. or something. They both ended up getting turned into animals at the end because of something, but Atalanta was badass, even after allowing Hipposomething to win.
3. One of my long standing favourites; Psyche. I like Rick Riordan's variation the most not only because it was the first that I read but because it is one of the myths that gives Psyche the most credit over a mistake, etc.
Psyche was a princess with two other sisters that was stunningly drop dead gorgeous. It was to the point that she had guys lined up just to admire her, appreciate her, everything. The problem with being a beautiful and privileged woman in Ancient Greece is that the moment you are even being known for being beautiful, Aphrodite's going to start tracking you in case you slip up. Psyche was very modest, doing her best not to anger the goddess of beauty, but other people didn't have the same consideration and eventually began to compare her to Aphrodite, saying she was her reincarnation or that she was prettier than her, a goddess herself. The worst part about all of Psyche's admirers was that none of them ever dared ask her out. They just admired. How frustrating is that?!
Aphrodite blew a fuse, and sent her son, Eros, to deal with things. In this version of the myth, it is prophesized that Psyche has to meet her husband by jumping off a cliff. Psyche, weirdly okay with the prospect of quite literally hitting rock bottom tells her parents that she'll be fine even if she does die and it's a prophecy so therefore she should probably go along with it.
And so she jumps. And gets caught by the world's best wingman and windman, Zephyrus. I named my horse in Red Dead Redemption 2 after him. Zephyrus whisks her away to a really nice home hidden away from the entire world and Psyche is to meet her husband there. She has no clue who the hell he is, still, but spends what time she has alone at the home during the day realizing how surreal it is- literally, riches everywhere.
At night, she meets her alleged husband. He refuses to be seen outside of the darkness, but he gives Psyche a reason for loving her that doesn't have to do with her looks, and Psyche, with tragically low standards, falls in love. She spends a good bit of time with him, but being alone with someone who won't tell you their name aside from being referred to as 'Husband' and only appearing in the darkness gets old, even though he's got the perfect personality and devotion. Eventually, she convinced him to let her sisters visit during the day.
Her sisters, two incomparable and jealous princesses, essentially cause Psyche to decide to find out her husband's identity. She's already under the impression that he's protecting her from Aphrodite's wrath and that's why she can't know anything, but her sisters make her fear the worst. So one day, she lights a candle at night, tiptoes over, and shines it over him. She's married to Eros. Psyche accidentally spills hot wax on his shoulder, and Eros wakes up. He then entirely abandons her, because SHE WASN'T SUPPOSED TO DO THAT. But I don't blame her, even without the sisters being married to a mystery man is weird. Like, come on.
Eros goes back to his mother and Psyche does her best to desperately try to find him. Also, in the middle of that, she convinces both of her sisters to jump off of cliffs to 'meet Eros' but really, they fall to their deaths. Evil. Before finding him, she just ends up cleaning the temples of goddesses Demeter and Hera, who both will remember that. She finally makes her way to Aphrodite's residence, somehow, who's been trying to hunt her down and kill her for 'breaking Eros' heart' the entire time. Also, Psyche's pregnant. Aphrodite beats up a pregnant woman, and Psyche takes it the way Chris Rock took that punch. She just asks for a chance to prove her love to Eros so they can be together, etcetera etcetera with Aphrodite's blessing. So Aphrodite decides to give her 3 impossible tasks.
I can't be bothered to go through the tasks, but they are pretty impossible. Demeter helps with the first one secretly, while Hera helps with the second. And they call up their brother and Hera's baby daddy Zeus (yes, that sentence is grammatically correct) to help with the third one. Aphrodite gives a fourth task, getting what is referred to as Persephone's 'essence of beauty'. At this point, Eros is kind of awake and his shoulder hurts like hell. He's literally lovesick and heartbroken, and his mom isn't helping make him any less bedridden. He does communicate with Psyche a little bit through a tower, offering her some advice. So Psyche travels to the Underworld, gets a box of it from Persephone, but then on her return back, she opens the box- because she thinks, pregnant, tired, and overworked, she deserves some, too. The only thing inside is the essence of death, and, well, it does what it sounds like. Persephone meant it to harm (but not kill) Aphrodite, a goddess, but Psyche is mortal. Uh oh.
She drops dead, Eros senses it, and drags her body over to Olympus. He calls all the gods to attention, and despite Aphrodite's protests, argues the case that Psyche deserves to be brought back, if not as a goddess. The gods agree and Psyche is brought back immortal, to be with Eros forever or whatever. I don't really care for that part although it is sentimental, I care about how they gave Psyche a sick pair of butterfly wings because it perfectly paralleled Eros's angel wings. So cool
Small fun fact-Psyche inspires a bit of Zara Zabroda's symbolism (BUT NOTHING MORE. NOTHING MORE.). Zara owns butterfly wings, and her IKIGAI account's profile photo is Psyche. Yeah, Zara Zabroda absolutely has a big head.
Note- I haven't actually read these in years so there's definitely a chance I misremembered them. But I really like greek mythology and its symbolism in writing so the moment I saw this post I wanted to jump on it. Another fun fact- the constellation of the 13th zodiac, Opiuchus, is, in Greek mythology, representing of the demigod Asclepius and it is usually most visible over Japan. Asclepius literally cured death before the gods chose to kill him themselves, so if you want some symbolism for Karakura's heavy themes of murder, there you go.