Monteith, who played one of the lead male characters, Finn Hudson, in the TV series Glee, was 31 years old. He was found in his hotel room on the 21st floor at around noon on Saturday.
His body was found after he failed to check out of the hotel, and staff at the Fairmont Pacific Rim Hotel went to his room.
Coroner Lisa Lapointe said: “We do not have a great deal of information as to cause of death.”
I am totally heartbroken right now. I love Cory so much this hurts my heart.
Lea Michele, his Glee co-star and real-life girlfriend, said in an interview with People magazine that she loved and supported him and was proud he was seeking help.
“We are in shock and mourning this tragic loss,” his representatives at Viewpoint Public Relations in Los Angeles said in a statement.
Stars from the show have also taken to Twitter to express their sorrow including Iqbal Theba, who played Principal Higgins, and Lauren Potter, who played Becky Jackson (see tweets, above).