Celebrity

TheGossip GirlandBuffy the Vampire Slayeractor died at 39 years old.

The world is mourning the loss ofMichelle Trachtenberg.

However, her cause of death has yet to be confirmed.

Michelle Trachtenberg

From herBuffyandGossip Girlco-stars to celeb mentors like Kim Cattrall and Rosie ODonnell, many stars gave tributes.

Read their reactions below.

You knew when she entered a room because the vibration changed.

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Everything she did, she did 200%, she wrote.

She laughed the fullest at someone’s joke, Lively continued.

You take for granted that you get the chance to see an old friend, she wrote.

Sarah Michelle Gellar and Michelle Trachtenberg

To paraphrase, the real tragedies in life are the ones that blindside you on an idle Tuesday.

Michelle, listen to me.

I will always love you.

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The hardest thing in this world, is to live in it.

I will be brave.

I will live… for you, she wrote with three heartbreak emojis.

Kim Cattrall and Michelle Trachtenberg in ‘Ice Princess’

Our first Nick movie star has departed us!!

She was my friend and now she rests!!

Check on your people!!!

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You are so loved and missed, Eugenie wrote.

Thank you for so many memories of laughter and fun.

You were so thoughtful and generous and soooo funny.

Alyson Hannigan and Michelle Trachtenberg

When I met this girl 17 years ago I knew wed be friends, she wrote.

Ill miss our late night calls that no one should ever hear but us.

She was always in my corner.

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Momsen then wrote a note directly to Trachtenberg.

I will miss you everyday my love, she said, in part.

I hope youre f*cking up heaven for both of us.

Rest in peace sweet Michelle, she captioned the post with a heartbreak emoji.

Michelle was one of a kind, he wrote.

I remember her coming on set for the first time and just absolutely owning it.

Just a terrible loss.

I loved her very much, she said.

She struggled the last few years.

I wish I could have helped.

Thinking of her and the family.

Michelle was so funny, kind, and talented, they wrote.

She was a delight to have on set and will be deeply missed.

Our thoughts are with her family.

Chris Colfer

Gleestar Colferreflected on his friendshipwith Trachtenberg in an Instagram tribute.

Michelle was the absolute sweetest and one of the most supportive people I knew, he wrote.

Im so lucky I got to be her friend.

Alyson Hannigan

Hannigan shared throwbackphotos with Trachtenbergfrom theirBuffydays on Instagram.

I am deeply saddened by the news of Michelles passing, she captioned the post.

She brought a loving energy to the set of Buffy.

My thoughts are with Michelles family and friends.

We shared countless laughs during filming, over the phone…

Her captivating stories are so entertaining that you cant help but want to hear more!

So very sad… horrible news, he wrote.

RIP and prayers to her and her family.

We have lost a beautiful soul, he wrote.

Michelle was fiercely intelligent, howlingly funny and a very talented person.

She died much too young, and leaves behind scores of people who knew and loved her."

So young, so talented and so sweet!

The episode was an idea I had about babysitting [being] a total nightmare.

But Michelle was nothing like her character and even this young, we got along wonderfully.

This article was originally published onFeb.