In Glee's six seasons, the show has seen massive highs and tragic lows, and ET was there for it all.
While the Fox hit became a TV phenomenon, winning four Golden Globes and six Emmys, the tragic and sudden death of star Cory Monteith in 2013 from a mixed drug toxicity forced the show to change everything.
"It used to, of course, end with Cory and Lea [Michele]," co-creator Ryan Murphy said. "It was a much more micro relationship ending, but I think that we've taken the heart of what we were going to do and expanded it so it feels sort of more macro and universal."
The Glee finale comes full circle with a look back at what made everyone join the club in the first place.
"It is a flashback of what happened during the pilot that we didn't see," star Kevin McHale said. "It's kind of fun to get to see why everybody signed up for glee club."
If the show takes fans down memory lane, filming the episode was even more nostalgic for the show's stars. Lea Michele shared that she savored the last moments of being on set.
"During the last two weeks of the show it started sinking in," Michele said. "Every day was like, 'This is my last dance rehearsal! This is my last fitting!'"
While the show isn't going out the way it was originally intended, Murphy assured ET that it will not disappoint.
"I feel that everything that I've been reading for four years about what the fans want from Glee is what they're going to get," Murphy said. "It's a very optimistic, uplifting, happy bow on everything."
Wrapping up loose ends could have been especially tricky for Glee, which has tackled every subject under the sun, including same-sex relationships, bullying, teen suicide and texting behind the wheel. For a show that's said so much about so many topics, Jane Lynch boils the main message down to this.
"We're all created equal in the eyes of God if you will, or whoever is the creator," she said.
The two-hour Glee series finale airs tonight at 8 p.m. on Fox.