Sarah Michelle Gellar Shares Heartbreaking Shannen Doherty Tribute: 'There Was So Much Love'

"How do you possibly find the right words to sum up 30 years of friendship?" began the actress, reflecting on her decades-long friendship with the late Shannen Doherty.

Sarah Michelle Gellar is honoring her late friend Shannen Doherty -- and urging her fans to do the same by supporting causes close to the Beverly Hills, 90210 star's heart.

Gellar and Doherty have been best friends for decades, with both appearing on The WB at the same time thanks to their shows Buffy the Vampire Slayer and Charmed in the '90s. On Monday, one day after the world learned Doherty died Saturday at the age of 53 following a years-long battle with cancer, Gellar took to social media to pay tribute.

"How do you possibly find the right words to sum up 30 years of friendship? I keep reminding myself it only hurts this much because, there was so much love," Gellar, 47, began, alongside a carousel of photos of the pair at different stages in their lives. "Thank you, for all your kind words and support."

"I love all the messages about how @theshando was important to you. So let's honor her. More than anything, Shan loves animals, especially dogs. In her memory let's support our favorite animal charities," Gellar continued. "Whether that's donating money, stopping by your local shelter and just offering cuddles and walks to animals housed there or even just tagging them in the comments so other people can learn about their work."

She concluded, "I know that would make our girl happy (and illicit that deep throaty laugh we all loved) 💔" before tagging The Lange Foundation in the comments.

Stars Pay Tribute to Shannen Doherty, 'Beverly Hills, 90210' Actress Dead at 53 After Cancer Battle

Gellar also received support from other celebrity friends in the replies.

"Beautiful way to honor her, you always get it right SMG ♥️💔♥️," wrote Rebecca Gayheart, while former Real Housewives of Beverly Hills star and longtime Gellar friend Crystal Kung Minkoff added, "I'm so sorry."

"Perfectly said. I know how close you two were," added Kristin Chenoweth. "She is flying with the angels now! ThunderPup and i will be donating to vanderpump dogs! 🐕"

Wrote Nicole "Snooki" Polizzi: "I am so sorry for your loss. Love you forever."

Shannen Doherty Announced as Cohost of 'Charmed' Rewatch Podcast Shortly Before Death

Earlier this year, Gellar praised Doherty for being there for her during the pandemic -- appearing on the late actress' Let's Be Clear with Shannen Doherty podcast to thank her for helping her and her family.

"You gave my children such a life in Covid and I was really struggling with how to give them that freedom and that room to be kids and have adventures," Gellar, who shares daughter Charlotte and son Rocky with husband Freddie Prinze Jr. told Doherty.

"And you opened your home to us in COVID in a way that I will for the rest of my life be grateful for," she continued.

"You gave them adventures and just, freedom. And I can never repay that because that was such a difficult time, and so seeing my kids that happy and giving me a break," Gellar explained. "People don't know this, but Shannen sat there sometimes while they were on Zoom school and helped them and we would have blackouts and she would plan adventures."

See how more celebrities honored Doherty following her death here.

Sarah Michelle Gellar 'Grateful' to Shannen Doherty for Being There for Her Kids During Covid