Cory Monteith, who played heart throb Finn Hudson in the Fox hit "Glee," was found dead in a Vancouver hotel room on Saturday, police said. He was 31.
Police said the cause of death was not immediately apparent, but they ruled out foul play.
Medical examiners will conduct an autopsy on Monday.
Monteith's body was discovered by staff members at the Fairmont Pacific Rim Hotel after he missed his checkout time, acting Chief Constable Doug LePard told reporters.
Monteith apparently had several people over to his room at one point Friday night, but LePard said Monteith, who had checked in July 6, was seen on hotel surveillance video returning to his room in the early morning hours by himself.
The glue of 'Glee'
Adam Shankman, who directed an episode for each of the past three seasons, told CNN's Poppy Harlow that he had talked to Monteith on Saturday morning. The actor said he wanted to come down to California to Jet Ski.
Shankman said Monteith was the glue of "Glee." He was always welcoming, whether it was to a guest director or a new cast member, Shankman said.
The actor knew all of his lines when filming began each time and would congratulate his fellow cast members when he thought they did well.
"He showed up every day and he was a delight," Shankman said.
'My heart is broken'
One of his castmates on "Glee," Mark Salling, tweeted a simple "no" after police held their news conference.
Dot-Marie Jones, who plays the football coach at the fictional William McKinley High tweeted: "I have no words! My heart is broken. Cory was not only a hell of a friend, he was one amazing man that I will hold close to my heart forever.
"I am blessed to have worked with him and love him so much! My heart is with his family and our whole Glee family! I love you all!"
Offscreen, Monteith was dating co-star Lea Michele.
He was madly in love with her, Shankman said. "He felt like it had renewed his spirit."
Reps for the actress asked Sunday "that everyone kindly respect Lea's privacy during this devastating time."
Struggles with substance abuse
Monteith spent time in rehab this year, checking into a drug addiction treatment facility in late March.
He had been frank about his struggles with substance abuse, telling Parade magazine in 2011 that he began using drugs at 13, and by 19 went into rehab after his mother and friends intervened.
"I had several interactions with him yesterday where he said that he was doing amazing," Shankman said. "He even said I am feeling fantastic. I'm like everybody else, really devastated and confused by what happened."
Awards for show
Monteith had been on the musical comedy show since it began in 2009.
On the show, Monteith played the dim quarterback of the football team at the Ohio high school who is forced to join the glee club. After graduation, he comes back to town and helps direct a musical at the school.
In 2011, he won a Teen Choice Award for top actor in a comedy. The show's cast won a Screen Actors Guild Award for an ensemble in a comedy the previous year.