The 44-year-old English actress plays wicked witch Bellatrix Lestrange who plots Harry Potter’s downfall with ultimate evil enemy Lord Voldemort in the film franchise, which is based on the books written by J.K. Rowling.
Helena has divulged her “love” for the nasty character but admitted that giving birth to her second child Nell with director Tim Burton in 2007 made filming the movies more physically challenging.
"I love Bellatrix," Helena told the BBC. "She is very energetic. At times it was quite hard, because one of the films I did just after giving birth. I was required to jump up and down and do all sorts of things. My pelvic floor, frankly, really wasn't up to it."
The actress appears in the Harry Potter films alongside Julie Walters, who plays Ron Weasley’s caring mother Molly.
Helena joked that when shooting the final wizardry movie, Harry Potter and the Deathly Hallows: Part Two - due out in summer 2011 - both actresses injured themselves during a climatic fight scene.
"In the next one me and Julie Walters have a duel at the end and we both put our backs out," she laughed."My chiropractor says, 'You have to warm up before you do any spells.' There's a lot of throwing your arm round."