Why Twitter is obsessed with the Charmed witches right now

The stars of the classic witches TV series Charmed - Rose McGowan, Alyssa Milano and Holly Marie Combs - are doing some serious good in the world right now.

Milano, who played Phoebe Halliwell for the series' entire run (1999-2006), has helped to popularise the hashtag #MeToo on Twitter. The hashtag is part of a campaign to encourage women, and men, who have been sexually harassed or assaulted to share #MeToo online. The idea, said Milano, is to give "a sense of the magnitude of the problem".

Milano's #MeToo tweet has now had 57,000 replies and 20,000 retweets.

Several other celebrities have joined in solidarity by tweeting '#MeToo', including Lady Gaga, Will & Grace star Debra Messing, and True Blood actress Anna Paquin.

The Dawson's Creek star James Van Der Beek and Brooklyn Nine-Nine comedian Terry Crews have also come forward with their own stories of abuse in Hollywood.

Milano has expressed support for Weinstein's accusers. "To the women who have come forward against a system that is designed to keep you silent, I stand in awe of you and appreciate you and your fortitude," she wrote.

"It is not easy to disclose such experiences, especially in the public eye. Your strength will inspire others. Thank you, thank you, thank you, for fighting this battle so hopefully my daughter won't have to."

Rose McGowan - who played Paige Matthews on the show - is, of course, at the heart of the scandal surrounding Harvey Weinstein.

She was one of the first actresses - along with Ashley Judd- to go public with allegations against Harvey Weinstein. She has accused the movie producer of rape, which he denies.

Her decision has encouraged other women to speak out, earning her the title 'the voice of the Weinstein resistance'. So galvanised are her followers that they've started calling themselves #ROSEARMY.

She's also not afraid to use Charmed references...

Meanwhile, Holly Marie Combs - aka Piper Halliwell on the series - is a committed animal rights activist. For instance, she has produced a documentary on the fight to preserve sea turtles in Costa Rica, and is on the board of advisors of the Wildlife Conservation Film Festival.

Over the past few weeks, she has been very vocal in her support of her Charmed co-stars, especially McGowan.

Twitter/@H_Combs/@Variety

And she isn't afraid of weighing into heated political debates like gun control, either.

Finally, a shout-out to one of the original stars of Charmed, Shannen Doherty. For the past 18 months, the actress - who played Prue Halliwell for the first three seasons of the show - has been using social media to document her fight against breast cancer.

Doherty hasn't shied away from sharing details of the most difficult parts of her treatment, from shaving off her hair...

...to the challenges of chemotherapy.

Fortunately, the actress has been in remission since April of this year.

In a throwback image she shared on Instagram at the weekend to mark Breast Cancer Awareness Month, she wrote: "Cancer has so many phases. Shock, denial, acceptance, anger, resentment, rebellion, fear, appreciation, beauty. Remission. Even then, the phases keep coming. Cancer is with you forever... You still go thru the roller coaster of emotions. You still need support and love. And you can still grasp life and live, live live."

To adapt Tina Fey's legendary Saturday Night Live joke: "Witches get stuff done."