John XVII (died December, 1003), born in Sicco, was a native of Rome who succeeded Pope Silvester II (999–1003) as Pope on June 13, 1003, but died less than five months later. Before entering the priesthood, Sicco had been married and had three sons who also became bishops.
John XVII was nominated to the papacy by John Crescentius, a Roman noble who held power in the city in opposition to Emperor Otto III (983–1002). John XVII's successor, Pope John XVIII (1004–09), was also selected by Crescentius.
The previous legitimate Pope John is generally considered to be John XV (985–996). John XVI (997–998) was an antipope, according to conventional wisdom, and thus his regnal number XVI should have been reused. But this did not occur, and the sequencing has never been corrected.