St. Ignatius of Antioch, an Eastern saint, (1st century AD) acknowledged the Roman Primacy. (Introduction of his letter to the Romans)
St Irenaeus, bishop of Lyons (2nd century AD) acknowledger Rome’s “superior authority”:
[quote=St.Iranaeus]Because it would be too long in such a volume as this to enumerate the of all the churches, we point to the tradition of that very great and very ancient and universally known Church, which was founded and established at Rome, by the two most glorious Apostles, Peter and Paul: we point I say, to the tradition which this Church has from the Apostles, and to her faith proclaimed to men which comes down to our time through the succession of her bishops, and so we put to shame . . . all who assemble in unauthorized meetings. For with this Church, because of its superior authority, every Church must agree – that is the faithful everywhere – in communion with which Church the tradition of the Apostles has been always preserved by those who are everywhere
(taken from his work “Adversus Haereses” (3:3:2))
Roman emperor Aurelian acknowledged the primacy or Rome . According to the Catholic encyclopedia:
[quote=Catholic Encyclopedia, “The Pope”]Equally noteworthy is the action of Emperor Aurelian in 270. A synod of bishops had condemned Paul of Samosata, Patriarch of Alexandria, on a charge of heresy, and had elected Domnus bishop in his place. Paul refused to withdraw, and appeal was made to the civil power. The emperor decreed that he who was acknowledged by the bishops of Italy and the Bishop of Rome, must be recognized as rightful occupant of the see. The incident proves that even the pagans themselves knew well that communion with the Roman See was the essential mark of all Christian Churches. That the imperial Government was well aware of the position of the pope among Christians derives additional confirmation from the saying of St. Cyprian that Decius would have sooner heard of the proclamation of a rival emperor than of the election of a new pope to fill the place of the martyred Fabian (Ep. 55:9).
Look on more of the primacy of Rome here: newadvent.org/cathen/12260a.htm
Numerous other saints, eastern and western, have given testimony to the Supremacy of the Roman Pontiff.