Princess Eugenie is mourning the death of her longtime friend and actress Michelle Trachtenberg — who was found dead inside her New York City apartment Wednesday.

“Goodbye special friend. You are so loved and missed. Thank you for so many memories of laughter and fun. You were so thoughtful and generous and soooo funny,” the British royal penned on her Instagram Story Thursday.

“My favourite was listening to you order food, always done with precision so you got exactly what we all wanted.”

Eugenie added, “I’m thinking of you up there friend, of your spirit that was so bright and your joy you brought so many.”

Along with the heartfelt tribute, Eugenie, 34, shared a throwback photo of herself hugging the “Gossip Girl” actress as they both flashed big smiles for the camera.

The emotional message from the princess — the younger daughter of Prince Andrew and Sarah Ferguson — came one day after Trachtenberg’s tragic death at age 39.

The “Buffy the Vampire Slayer” alum — who underwent a liver transplant shortly before her passing — was found in her apartment by her mother, Lana Trachtenberg.

Michelle’s cause of death was ruled “undetermined” after her family objected to an autopsy.

“Under public health law, families may object to autopsy based on religious belief, and provided there is no suspicion of criminality or compelling public health reason to proceed with autopsy, the medical examiner honors the objection,” a rep for the Office of Chief Medical Examiner in New York told Page Six Thursday.

Many friends and former castmates have taken to social media to grieve the actress’ death following the news of her untimely passing.

Blake Lively — who co-starred with Michelle in “Gossip Girl” — described her as “fiercely loyal to her friends and brave for those she loved” in an Instagram Story post shared Wednesday.

Meanwhile, “Buffy” star Sarah Michelle Gellar shared a statement referencing the show’s Season 5 finale to honor her late friend and onscreen sister.

“‘Michelle, listen to me. Listen. I love you. I will always love you. The hardest thing in this world, is to live in it. I will be brave. I will live… for you,’” Gellar wrote via Instagram Thursday.

One year before Michelle’s death, she fired back at haters on social media who claimed she looked “sick.”

“Explain to me how I look sick,” she replied after fans criticized her physical appearance. “Did you lose a calendar and not realize I’m not 14. I’m 38. How sad for you to leave such a comment.”

Despite saying that she was “happy and healthy” in January 2024, Michelle’s friend Amanda de Cadenet said that the actress “knew that death was a high possibility” within the past six months.

“I am only sorry that the outcome was not a better one,” de Cadenet wrote in part via Instagram Wednesday. “Wishing you a peaceful transition sweet friend and may your spirit finally rest.”