Award-winning children's and YA author Marcus Sedgwick has died. He was 54.

“Marcus had extraordinary range, curiosity, and an uncanny knack for prose. He was a mentor, and a gracious friend. I will miss him,” editor Simon Boughton told SLJ. Boughton worked with Sedgwick on his Printz winners and many other titles.

Over more than 20 years, Sedgwick wrote more than 40 books, spanning from picture books to adult titles. His most acclaimed titles were YA. He earned the 2014 Printz Award (Midwinterblood) and two Printz Honors (The Ghosts of Heaven, 2016 and Revolver, 2011).

Sedgwick's literary agency, RCW Literacy Agency, released this statement: 

"It is with deep regret that RCW announces the unexpected death of author Marcus Sedgwick.

"Marcus Sedgwick was a prizewinning and beloved author of over 40 extraordinary books for adults and young adults, of novels for younger people, of non-fiction and academic essays. His books were shortlisted for over thirty awards, including the Carnegie Medal (five times), the Edgar Allan Poe Award (twice) and the Guardian Children’s Fiction Prize (four times). He is also the most noted author in the history of the Printz Award, with one win and two honor books. He won the Branford Boase award for his debut novel, Floodland, and the Booktrust Teenage Prize for My Swordhand is Singing.

"Marcus was born and raised in a small village in East Kent in the south-east of England and lived most recently in the south of France.

"His family and close friends request privacy at this very sad and difficult time."

Fans and fellow authors took to Twitter to express their shock and sadness at the sudden loss.

His agent at RCW, Claire Wilson, wrote "Marcus was at the start of everything for me—his work reminded me of what children’s books can do and why they matter. I will always be grateful for the honour of getting to represent him, and finding such a kind, wise and funny person behind the writing. It is an immense loss."

“Devastated to hear the terrible news about the tragically premature death of Marcus Sedgwick. He was a superb writer, and did things that no one else was doing in YA,” tweeted author Anthony McGowan, winner of the 2020 CILIP Carnegie Medal for Lark.

The New York City School Library System Twitter account posted “Thank you for your work, #marcussedgwick. You have enlightened the lives of many young readers and will be missed by all.”

And author Thomas Taylor tweeted “Marcus was a dazzling storyteller, a creative powerhouse, a deeply thoughtful and perceptive man, and a good, good friend.”

Sedgwick's most recent release was in October—All In Your Head, an adult title about the battle to get doctors to believe you are sick when you suffer from an "invisible" illness and the stigma and life that comes with chronic illness. Sedgwick had Chronic Fatigue Syndrome, also known as myalgic encephalomyelitis or ME/CFS. He was an advocate for the ME/CFS community and chronically ill.