Pope St Marcellus I was pope from May 308 to 309. He seems to have been an active administrator, doing much to reorganize the Church after the devastation caused by the persecutions of Diocletian.
He sparked the enmity, though, of those who had lapsed during this period by his demands that they do penance.
Both this and the vigour of his efforts to re-establish the Church seem to have contributed to his banishment by the Emperor Maxentius. He died not long thereafter.