.
According to these dates, the first one was pope when St.
Philomena was martyred in A.D. 302.
There were three popes "Marcel" apparently (Wikipedia):
Pope St. Marcellinus (Italian: Marcellino; died 1 April 304) was the head of the Catholic Church from 30 June 296 to his death in 304.[1] According to the Liberian Catalogue, he was a Roman, the son of a certain Projectus. His predecessor was Pope Caius.[2]
Marcellinus’ pontificate began at a time when Diocletian was Roman Emperor, but had not yet started to persecute the Christians. He left Christianity rather free and so the church’s membership grew. Caesar Galerius led the pagan movement against Christianity and arrived to bring up Diocletian against Christianity in the year 302: first Christian soldiers had to leave the army, later the Church's property was confiscated and Christian books were destroyed. After two fires in Diocletian’s palace he took harder measures against Christians: they had either to apostatize or they were sentenced to death.
The second was the immediate successor to the first (after
4 years of sedevacante):
Pope St. Marcellus I (Latin: Marcellus PP. I, Italian: Marcello I; died 309) was the head of the Catholic Church from May or June 308 to his death in 309.[1] He succeeded Pope Marcellinus after a considerable interregum. (304 - 308)
His third-class feast day is kept on January 16 in the extraordinary form of the Roman Rite.
The third has not been canonized a saint (even though he was
certainly a SAINT compared to John XXIII, Paul VI, or JPII!!!
HAHAHAHAHA):
Pope Marcellus II (Latin: Marcellus PP. II, Italian: Marcello II; 6 May 1501 – 1 May 1555), born Marcello Cervini degli Spannochi, was the head of the Catholic Church from 9 April 1555 to his death on 1 May, 1555. He succeeded Pope Julius III. Before his accession as pope he had been Cardinal-Priest of Santa Croce in Gerusalemme. He is the most recent pope to choose to retain his birth name as his regnal name upon his accession, as well as only the second and most recent pope to date to take the name "Marcellus" upon being elected. After his death, it would be 423 years before another pope would choose a name with an ordinal number less than IV (John Paul I). He died on the 22nd day after his election, in the same month of April 1555. Pope Marcellus II was Pontiff for less than one month. He was one of the popes during the Council of Trent (December 13, 1545 to December 4, 1563),
although he ironically did not act as Pope during Trent, since it was not in session
during the month of April, the only month Marcellus II occupied the Chair of St. Peter.
It seems he suffered death due to the rigors of Holy Week!!