John J. Curulewski (October 3, 1950 – February 13, 1988) was an American musician who was one of the original members of Styx.

In 1969 Curulewski joined the Chicago-based band TW4, featuring college friends Dennis DeYoung, Chuck Panozzo, and John Panozzo. The group evolved into Styx by 1972.^[1] Curulewski played guitar and sang occasional lead vocals on the band's first five studio albums, released from 1972 to 1975.^[2] Just after the recording of the album Equinox in 1975, Curulewski left Styx to spend more time with his family, and was replaced by Tommy Shaw.^[3]

After his career with Styx, Curulewski became a guitar teacher in the Chicago area and played occasionally in local bands. He died at his home in Midlothian, Illinois on February 13, 1988, from a brain aneurysm, and was buried at St. Benedict Catholic Cemetery in Crestwood. He was survived by his wife and their son.^[4][5]