Pope Leo V (died c. February 904) was Pope from July 903 to his death in 904. He was pope during the period known as the Saeculum obscurum. He was thrown into prison in September 903 by the Antipope Christopher, and was probably killed at the start of the pontificate of Pope Sergius III. If his deposition is not considered valid (as in the modern Vatican list), then his papacy may be considered to have ended with his death in 904.