Since she burst onto the scene in Grey's Anatomy over 14 years ago, the actress has been blonde, but for her new role in Netflix's upcoming series Firefly Lane, she had a total makeover and was almost completely unrecognisable on Instagram this morning with dark brunette hair.
Here's the Katherine we're used to seeing:
And this is her brunette:
The 40-year-old uploaded a few progress pics to Instagram before sharing her final look, noting that the process would take a while (it took three hours) so she stocked up on champagne and books.
This article originally appeared on Marie Claire.