Of all the female characters in Shakespeare's tragedies, Lady Macbeth stands out in ambition and perseverance. Discuss.
This is a huge question. One for which I narrowed the focus to a discussion of the female characters in Shakespeare's tragedies. I'm afraid that there are a least a few more female characters who are to be noted for their ambition and perseverance, which means that Lady Macbeth does not stand out in the way that you suggest. It must also be noted that Lady Macbeth ends the play a broken, guilt-ridden woman, which lessens the overall impression of her strength.
The other strong and determined female characters I mention here may not all invoke the dark forces of evil to assist them, or ask directly to be "unsex"-ed, but they definitely are female characters who act in as "masculine" and determined a demeanor as Lady Macbeth.
First, I'll mention Cleopatra. She is the driving force in this play, and is able to bend Antony to her will, taunting and manipulating him in a similar fashion to Lady Macbeth's behaviour towards Macbeth. She also, like Lady Macbeth is not always "nice." She can be mean and vindictive, and this is especially evident with her servants. Cleopatra is a strong and demanding force to be reckoned with in this play, and much of the action revolves around her desires and intentions. She is already the leader of her country, and more than matches Lady Macbeth in ambition and perseverance.
Also strong and determined to have her way is the very young heroine, Juliet. She is no shy retiring flower, and takes the masculine lead in asking her love, Romeo, when, where and at what time he intends to "put up or shut up" and make her his bride. She also outshines Romeo in bravery once he is banished and they both visit the Friar for his advice/help. Whereas Romeo cowers and must be demanded to "act like a man" by the Friar, Juliet enters, dagger at the ready, threatening to kill herself if the Friar doesn't help her. She is strong, ambitious in love and extremely persistent.
Some other female characters in the tragedies who display outstanding ambition and perseverance are Regan and Goneril in King Lear, Tamora in Titus Andronicus, and even Portia in Julius Caesar (though her stage time is limited) expresses a strong determination and ambition to be an equal partner to Brutus.
So, while there is no denying that, in the early Acts of Macbeth, Lady Macbeth exhibits uncharacteristic strength for a woman of Shakespeare's time, she is certainly not the sole female created by Shakespeare with these characteristics. And we haven't even started on the strong women of the comedies.
Please follow the link below to the Enotes guide to Shakespeare's Women for more on strong women in Shakespeare 's tragedies and comedies.