Sarah Michelle Gellar's Birthday Message For Shannen Doherty Will Have You in Tears

Sarah Michelle Gellar has a lot of admiration for her longtime friend Shannen Doherty. On Wednesday, the Buffy the Vampire Slayer actress celebrated Shannen's 46th birthday with a heartfelt post on Instagram. "Where do I even start with this birthday girl?!?" she wrote alongside a throwback picture of them sharing a laugh. "She's everything. She's inspired me . . . well since . . . even before I called her a friend. But over the last year, I have watched her inspire and give hope to the world," she continued, referring to Shannen's decision to document her courageous battle with breast cancer since revealing her diagnosis in August 2015.

"I thought I knew how tough she was, but I didn't even have a clue to her power," she added. "When I think twice about leaving the house without makeup, Shannen shaved her head on the public stage. While I fiercely guard my privacy, she opened her life, her struggles, her fears and her journey to help people she has never even met. She is a true friend to everyone. Shannon also has the greatest laugh in the world, which is why I chose this picture. To the fiercest, most loyal friend I know....let's party like it's your birthday!!! I love you."