In J.K. Rowling's Harry Potter series of novels, Bellatrix Lestrange is a death eater and cousin of Harry's Godfather, Sirius Black. While at Hogwarts, Bellatrix was a member of Slytherin House. During the First Wizarding War, she used the Cruciatus curse on Aurors Frank and Alice Longbottom. She was sentenced to life in Azkaban prison for this crime. She later escaped from Azkaban and joined Voldemort just prior to the Second Wizarding War. She was killed during the war by Molly Weasley.
Bellatrix is the third brightest star in the constellation Orion.
The name Bellatrix is Latin, and means "female warrior." In 2014, 9 girls were named Bellatrix in the United States.
Although Bellatrix Lestrange isn't the best character to name a child after, it's a much cooler way of getting to Bella if you like that nickname.