Brows are always at the center of the beauty conversation. The ever-evolving trends breed "brow gurus" like Anastasia and Benefit, as well as new tweezing, waxing and futuristic brow-building technology all the time. Why? Because brows make the single biggest difference in how we look.

"Eyebrows are the most important thing on a woman's face," says celebrity makeup artist Victoria Duke. "They set the stage for our expressions, which have a huge impact on how we look." Examples? "Really thin eyebrows can make you look older" Duke continues, "a strong arch makes you look more confident; a full, soft brow makes you look youthful.... Shape and color matter."

Not everyone nails the perfect brow, however -- celebrities included. Duke says some of the worst celebrity brows of the moment include Nikki Minaj's over-exaggerated brows, Demi Lovato's thin, harshly shaped ones and Kate Middleton's shapeless brows.

But there is hope for recovery from unfortunate arches. Keep clicking to see which of your favorite celebrities have finally mastered their perfect brow. Sometimes, it takes a lifetime. Here, the famous faces that made it happen in 2015.

Then: What brows? Lucky for humankind, the pencil-only look was just a phase.

Now: They're grown back in again -- softer and fuller.

Images: Getty Images

Then: Way too high and unruly.

Now: The arch is grown in and darkened for a more polished, grown-up look.

Images: Getty Images

Then: Attention-grabbing brows. Long, bushy and much too dark for her hair color.

Now: Toned down with some trimming and plucking, but they still manage to command attention.

Images: Getty Images

Then: Natural is usually a good look, but this was a little too natural.

Now: Cleaned up, yet full with a nice arch -- these brows perfectly frame her eyes.

Images: Getty Images