Alcmene, Heracles' mother, is a granddaughter of the great hero Perseus. Because of her, Heracles gets tons of awesome hero genes, which help to make him so amazing. Some say that Alcmene's heritage is a big part of the reason that Zeus chooses to conceive a baby with her. Of course, the fact that she's smokin' hot is probably a factor as well.
It's said that Alcmene was incredibly faithful to her husband, Amphitryon, which is probably why Zeus decides to seduce her by disguising himself as her husband. (Maybe that's also why Hera, the goddess of marriage, didn't harass Alcmene all that much. Just a thought.) No one seems to hold a grudge against her even though she abandons Heracles in a field for fear of Hera. (Hey, what's a woman to do? Hera is pretty psychotic when it comes to Zeus' mistresses.) Although she was never considered a goddess, Alcmene was worshiped after she died.