Matthew Morrison thinks Glee had been in decline for several seasons.
The 36-year-old actor - who played teacher Will Schuester in the musical drama series - has criticised the programme for having a large cast with characters that the audience didn't connect with.
He said: "Glee had its heyday, and then it kind of just slowly started declining.
"There were just so many characters. There are a lot of people and a lot of story lines. It's one of the biggest casts on television. They have the New Directions, the original New Directions, and then you have the new New Directions ... The new ones didn't really click with people, so they had to start bringing back in the old people."
Of the show's Friday night slot, he added: "It's where shows go to die."