Bellatrix LeStrange came late in the series, but proved to be one of Voldemort's best supporters.
She got sent to Askaban after torturing Neville Longbottom's parents Frank and Alice to the point of insanity.
And the plot point does come up to subject, with Neville meeting the one person he hates the most.
She is also responsible for the deaths of many characters such as Sirius Black, Dobby, and Tonks.
Then she gets killed by Ron's mom Molly Weasley. The fuck?