See Birthday Girl Christina Hendricks’s Best Beauty Moments

It's Christina Hendricks's birthday! The red-hot bombshell welcomes her 40th birthday today. And as she gears up for Mad Men's final episodes to premiere, marking the end of an era in pop culture and retro style inspiration, she's still leading the charge off the screen in the old Hollywood glamour department. Specifically,, fans are undeniably captivated by the star’s vibrant hair hue, trademark crimson lips, and bombshell style.

Although the actress recently ditched her signature hair color for a more sun-kissed look, we’re enamored by Hendricks’s decision to make the drastic change. "I think everyone knows when you get a fresh haircut or you change your color, it sort of gives you a different attitude or gives you a little spring in your step," she tells InStyle. "So after 20 years of one color, it's fun to be something new. I like it a lot." Ditto.

In honor of the Mad Men star's birthday, see her changing looks through the years.

PHOTOS: Christina Hendricks's Best Beauty Moments