Károly Frenreisz (born 8 November 1946, Budapest, Hungary) is a Hungarian rock singer and songwriter.
Frenreisz first studied piano and then learned to play the clarinet, saxophone, and bass.
He played a significant role in getting Metró through the end of the sixties and being part of the era of modern experimental trends in music.
In 1971, he was a founding member of the band Locomotiv GT, where he was the bassist, brass player, and lead singer.
They had many hit songs, such as "Így szólt hozzám a dédapám" (from "A rohanás") and later, "Azt beszéli már az egész város" (1985).