Pop icon Madonna has paid tribute to her brother Christopher Ciccone on social media, saying "there will never be anyone like him".
Ciccone, a dancer, artist and author, died on Friday in the American state of Michigan aged 63.
His husband, British actor Ray Thacker, was by his side when he died.
Ciccone had cancer, the Associated Press reported.
Madonna, whose original name was Madonna Louise Ciccone, posted a tribute to her brother, saying he was "the closest human to me for so long".
Dance 'saved' Ciccone
"Discovering dance in our small Midwestern town saved me and then my brother came along, and it saved him too," Madonna wrote in an Instagram post.
"My ballet teacher, also named Christopher, created a safe space for my brother to be gay ... a word that was not spoken or even whispered where we lived.
"When I finally got the courage to go to New York to become a dancer, my brother followed.
"And again we took each other's hands, and we danced through the madness of New York City.
"We devoured art and music and film like hungry animals ... we were in the epicenter of all of these things exploding.
"We danced through the madness of the AIDS epidemic.
"We went to funerals and we cried, and we went dancing."
Christopher Ciccone and Madonna at the premier of her film Truth or Dare in 1991. (AP Photo: Julie Markes)
Ciccone's creative career
A dancer since his youth, Ciccone was deeply intertwined with his sister's rise in pop stardom in the 1980s.
He appeared in music videos including Lucky Star, was the tour director for Madonna's The Girlie Show tour and the art director for her Blond Ambition World Tour.
He also directed music videos for Dolly Parton and Tony Bennett.
For two decades, he was by her side, choreographing, directing, dressing and helping his sister.
He also interior-designed her homes in New York, Miami and Los Angeles.
Madonna described Ciccone as "a painter, a poet and a visionary".
"When it came to good taste, my brother was the Pope, and you had to kiss the ring to get his blessing," she said.
"We defied the Roman Catholic church, the police, the moral majority and all authority figures that got in the way of artistic freedom!
"My brother was right by my side."
Tell-all book about famous sister
In 2008, Ciccone released a bestselling autobiography called Life with My Sister Madonna.
He wrote about their strained relationship, her romantic entanglements as well as recollections from his time on tour with her.
Ciccone said that it was a bit like a marriage at times.
"It was a double-edged sword," he told Good Morning America in 2008.
The book, and his no-filter descriptions of the exploits of his sister's famous circle, took its toll on some of his Hollywood friendships too.
Several years later, in 2012, around the launch of a shoe collection he designed, he told The Standard that he and his sister were "on a perfectly personable level" and in contact.
"I don't work for her, and it's better this way," he said.
In recent years Ciccone relocated to Michigan's Lower Peninsula to be closer to family.
He married Thacker in 2016.
Madonna says the bond between her and brother Christopher Ciccone was "hard to explain". (Instagram: madonna)
'He's dancing somewhere'
Madonna did not go into details about Ciccone's condition, but said he had been in "so much pain".
"I'm glad he's not suffering anymore," she said.
"There will never be anyone like him.
"I know he's dancing somewhere."
Christoher Ciccone was one of Madonna's five siblings.
The pair's older brother, Anthony Ciccone, died in early 2023.
Their stepmother, Joan Clare Ciccone, died just a few weeks ago.
ABC with AP