The obvious choice:
We were discussing this in a literature class in terms of Antigone, the greek tragedy by Sophocles. She heroically stood up to King Creon in the name of her brother, risking her life in the face of deadly consequences.
Heroic Attributes: Bravery, Defiance, Beauty, Wisdom, Strength, Confidence, Endurance, Morality...
My top ten heroines are (in no specific order): Frida Kahlo, Ayn Rand, Anais Nin, Georgia O'keef, Amelia Earhart, Margaret Thatcher, Virginia Woolf, Gertrude Stein, Liz Phair, and Joan of Arc. I know this is a really broad collection, but they all have one thing in common. Each of these women went against the grain to achieve what was important to them. In the face of criticism and doubt, these women were heroes.
For class, I wrote about Frieda Kahlo:
The Broken Column, Frieda Kahlo
Who is your heroine?