Canadian actor Cory Monteith, 31-year-old heartthrob of Fox's musical comedy television series "Glee", was found dead on Saturday in his Vancouver hotel room, police said.
Police and paramedics found no signs of foul play and the cause of death was not clear, British Columbia Chief Coroner Lisa Lapointe said at a news conference.
Monteith had talked openly about struggles with substance abuse, and in April he completed voluntary treatment for unspecified substance addiction at a rehab facility. He had also been treated in a facility at age 19.
Asked whether Monteith had died of a drug overdose, Vancouver Police Department Acting Chief Doug LePard said he would "not discuss anything that we might have found in the room at this time."
On the hit series "Glee," Monteith played Finn Hudson, a high school football player turned enthusiastic singer in the glee club, or vocal group.
The actor grew up in Victoria, British Columbia, and told Parade magazine in 2011 about what he called a serious drug problem during his teenage years for which he received treatment.
Other people were in Monteith's Pacific Rim Hotel room on Friday night but evidence, including fob key entries, indicated he returned to his room by himself early on Saturday and was alone when he died, police said. He was due to check out of the hotel later that day.
The actor had been dead for several hours when his body was discovered by police and paramedics answering an emergency call, Lapointe said.
"The death of a young person is a tragedy for their family, friends and community," Lapointe said. "A sudden death is more shocking and our hearts go out to the family and friends who are mourning the loss of this young man."
Monteith's mother, Ann McGregor, lives in Victoria, where the actor grew up.
Monteith began his career in a number of small roles leading up to a recurring part between 2006 and 2007 in the ABC Family science-fiction drama "Kyle XY" and another role around the same time on the MTV series "Kaya."
But "Glee," a show set in the small town of Lima, Ohio, was Monteith's breakthrough role. A big part of the show was his character's on-again-off-again romance with glee club star Rachel Berry, an aspiring entertainer played by Lea Michele.
Monteith and Michele followed in the footsteps of their fictional counterparts by dating in real life. They appeared publicly together as recently as last month at a charity ball.
In recent episodes of the series, Rachel had left to attend college in New York while Finn stayed in Lima, where he worked at his father's auto repair shop and later got involved in helping lead his former school's glee club.
In a statement on their "Glee" Twitter page, the executive producers of the show and Fox said they were "deeply saddened by this tragic news".
"Cory was an exceptional talent and an even more exceptional person," the message said. "He was a true joy to work with and we will all miss him tremendously. Our thoughts and prayers are with his family and loved ones."
Singer and former "Glee" actress Kristin Chenoweth said in a message on Twitter: "You will be loved. Always."
Taylor Swift tweeted that she was "Speechless. And for the worst reason," while Rihanna posted that Monteith's death was "heartbreaking, my prayers are with all of his loved ones!"
Other tributes were posted by singers Lance Bass, LeAnn Rimes and Zooey Deschanel, who mourned the "absolutely tragic loss of a very talented young man."
An autopsy was set for Monday, LePard said.