In 1978, the God of Thunder and the Queen of Disco ignited one of music’s earliest and most electrifying genre crossovers.

Long before mashups were cool, KISS‘ Gene Simmons teamed with Donna Summer on his 1978 self-titled solo album, with the Queen of Disco laying down backing vocals on “Burning Up with Fever” & “Tunnel of Love.”

The duo may have performed distinctly different styles of music, but they shared the same legendary label, Casablanca Records, and had mutual respect for one another as artists.

“For quite a few years, Donna was the queen of disco–nobody touched her,” Simmons told Rolling Stone in a 2015 interview. “And unlike other disco artists of the era, Donna had credibility. She even had a duet with Barbra Streisand, which also, of course, became a huge smash [“Enough Is Enough (No More Tears)”].

“KISS was the first act on the new Casablanca Records label,” he added. “And then they signed Donna Summer, and the walls came a-tumblin’ down.

“We also happened to live in the same building in New York City at one point,” he continued. “I had the penthouse floor, and Donna lived on the first floor. …the Donna I remember was …gracious and charming. RIP Donna Summer.”