John McMullen (January 8, 1832 – July 4, 1883) was an Irish-born prelate of the bishop of the Roman Catholic Church.

McMullen was ordained to the priesthood in Rome by Archbishop Antonio Ligi-Bussi on June 20, 1858, for what was then the Diocese of Chicago.

During this time, he helped to establish the House of the Good Shepherd in Chicago, which cared for female former prostitutes.

He was a frequent visitor to the Cook County Jail and Bridewell House of Corrections, bringing newspapers and other reading material to the inmates.

When Duggan's mental state started to deteriorate, McMullen traveled to the Vatican in 1868 as a representative of the diocesan clergy to inform the pope.

After Foley's death, McMullen was named administrator of the diocese; he was renamed vicar general after the installation of Archbishop Patrick Feehan.

He traveled by stagecoach, buggy, lumber wagon, hand car and passenger coach on the train.

He also traveled to California, where he fell gravely ill. On July 4, 1883, John McMullen died from stomach cancer in Davenport, having served as bishop for less than two years.

Archbishop Feehan celebrated the Requiem Mass and Bishop Spalding preached the sermon.