Indeed. It's Eowyn in her encounter with the Witch-king, from Lord of the Rings:
'Hinder me? Thou fool. No living man may hinder me!'
Then Merry heard of all sounds in that hour the strangest. It seemed that Dernhelm laughed.... 'But no living man am I! You look upon a woman. Éowyn I am, Éomund's daughter. You stand between me and my lord and kin. Begone, if you be not deathless! For living or dark undead, I will smite you, if you touch him.'
The winged creature screamed at her, but the Ringwraith made no answer, and was silent, as if in sudden doubt. Very amazement for a moment conquered Merry's fear. He opened his eyes and the blackness was lifted from them. There some paces from him sat the great beast..., and above it loomed the Nazgûl Lord like a shadow of despair. A little to the left facing them stood she whom he had called Dernhelm. But the helm of her secrecy had fallen from her, and her bright hair... gleamed with pale gold upon her shoulders. Her eyes grey as the sea were hard and fell, and yet tears were on her cheek. A sword was in her hand, and she raised her shield against the horror of her enemy's eyes.
Éowyn it was, and Dernhelm also. For into Merry's mind flashed the memory of the face that he saw at the riding from Dunharrow: the face of one that goes seeking death, having no hope. Pity filled his heart..., and suddenly the slow-kindled courage of his race awoke. He clenched his hand. She should not die, so fair, so desperate. At least she should not die alone, unaided.
The face of their enemy was not turned towards him, but still he hardly dared to move.... Slowly, slowly he began to crawl aside; but the Black Captain, in doubt and malice intent upon the woman before him, heeded him no more than a worm in the mud.
Suddenly the great beast beat its hideous wings.... Again it leaped into the air, and then swiftly fell down upon Éowyn, shrieking, striking with beak and claw.
Still she did not blench: maiden of the Rohirrim, child of kings..., fair but terrible. A swift stroke she dealt, skilled and deadly. The outstretched neck she clove asunder, and the hewn head fell like a stone. Backward she sprang as the huge shape crashed to ruin, vast wings outspread, crumpled on the earth; and with its fall the shadow passed away. A light fell about her, and her hair shone in the sunrise.
Out of the wreck rose the Black Rider, tall and threatening, towering above her. With a cry of hatred that stung the very ears like venom he let fall his mace. Her shield was shivered in many pieces, and her arm was broken; she stumbled to her knees. He bent over her like a cloud, and his eyes glittered; he raised his mace to kill.