In 2007, Ronnie Vannucci Jr. (drummer for The Killers), who knew Campbell from a previous band, saw Neon Trees playing at a small venue in Las Vegas and was impressed.

In 2014, Glenn was featured as lead vocalist on "Born to Run," a song on Afrojack's debut studio album, Forget the World.

In 2015, Glenn joined the holiday music supergroup Band of Merrymakers for their album Welcome to Our Christmas Party.

In the video, Glenn is seen drinking from a bottle of alcohol, spitting on an altered image of Joseph Smith, making the LDS church's temple tokens with his hands, and painting a red 'X' on his face.

In the April 10, 2014, issue of Rolling Stone, Glenn revealed he was gay and discussed keeping his sexuality a secret throughout his life.

Regarding the Mormon faith he grew up with, Glenn stated in a 2012 interview: "The way I was raised and being a questioner, and getting a lot of my curiosities out early with drugs and alcohol, I think it's helped me maintain a more even keel where I'm not out of control.

"[12] It had been widely reported that Glenn and the other members of Neon Trees do not drink alcohol or use illicit drugs.