Character Analysis
The Duchess of Gloucester, Eleanor Cobham also likes to go by "Nell," her hubby's pet name for her. She might be "second woman in the realm" (2.1.45), but this girl's got dreams: Eleanor doesn't want to be #2 when she could be #1. Her husband gets mad at her for even giving voice to her lofty crown-stealing motives, but she sticks with it. She even hires witches to tell her what the future holds.
Turns out that's only a good idea in Macbeth. Er, wait—it wasn't a good idea there, either.
Anyway, Eleanor is totally caught with the witches, and for that, she's arrested, publicly humiliated, and banished. (The witches themselves are killed off, by the way.) Sure, nobles are scheming against her, but unlike her husband, Eleanor has actually committed the crime she's charged with... well, sort of, anyway—she's not actually practicing witchcraft; she's just hanging with witches.
Eventually, Eleanor becomes so overcome with shame that she asks Gloucester: "[T]each me to forget myself" (2.4.28). It's certainly not a harmonious end for Eleanor, and her downfall is the beginning of the end for her husband, too. But she also reminds us that ambition is not something exclusive to men. Eleanor is super ambitious, even though she already has almost everything—which shows just how deeply greedy aspirations run in this society.
Now, compared to people like Margaret and Suffolk, Eleanor doesn't seem all that bad. Sure, she has some major ambitions, but when things don't go her way and she gets in a whole boatload of trouble, she seems to learn something from the catastrophe. We don't know what will happen to her in exile on the Isle of Man, but it does seem possible that she's learned her lesson.