Saint Peter the Apostle 
Also known as Simon and Cephas, his feast is celebrated with St. Paul on the 29 th of June. The feast of the Chair of Peter, which stands for the World Unity of the Church is celebrated on the 22nd of February.
He was a fisherman, brother of Saint Andrew the Apostle who led him to Christ. The Lord gave him the name of "Peter" to indicate that he would be the rock on which the Church would be built.
He had miraculous healing powers, so that people were cured even by his shadow. (Acts 5:15) He was the first Bishop of the Church, we can say that He was the first Pope. He died as a martyr, crucified head downward because he claimed he was not worthy to die in the same manner as the Lord. St. Peter died around 64 A.D.
The Lord said to Simon: (Matthew 16:18-19) And I tell you, you are Peter, and on this rock I will build my church, and the gates of Hell will not prevail against it.
19 I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.
Peter in the words of some Fathers of the Church
Clement of Alexandria
"The blessed Peter, the chosen, the pre-eminent, the first among the disciples, for whom alone with himself the Savior paid the tribute [Matt. 17:27], quickly grasped and understood their meaning. And what does he say? `Behold, we have left all and have followed you'" [Matt. 19:27; Mark 10:28] (Who Is the Rich Man That is Saved? 21:3-5 [A.D. 200]).
Tertullian
"For though you think that heaven is still shut up, remember that the Lord left the keys of it to Peter here, and through him to the Church, which keys everyone will carry with him if he has been questioned and made a confession [of faith]" (Antidote Against the Scorpion 10 [A.D. 211]).
Tertullian
"The Lord said to Peter, 'On this rock I will build my Church, I have given you the keys of the kingdom of heaven [and] whatever you shall have bound or loosed on earth will be bound or loosed in heaven' [Matt. 16:18-19] . . . Upon you, he says, I will build my Church; and I will give to you the keys, not to the Church; and whatever you shall have bound or you shall have loosed, not what they shall have bound or they shall have loosed" (Modesty 21:9-10 [A.D. 220]).
The Letter of Clement to James
"Be it known to you, my lord, that Simon [Peter], who, for the sake of the true faith, and the most sure foundation of his doctrine, was set apart to be the foundation of the Church, and for this end was by Jesus Himself, with His truthful mouth, named Peter, the first-fruits of our Lord, the first of the apostles; to whom first the Father revealed the Son; whom the Christ, with good reason, blessed; the called, and elect" (Letter of Clement to James 2 [A.D. 221])
Origin
"If we were to attend carefully to the gospels, we should also find, in relation to those things which seem to be common to Peter . . . a great difference and a preeminence in the things [Jesus] said to Peter, compared with the second class [of apostles]. For it is no small difference that Peter received the keys not of one heaven but of more, and in order that whatsoever things he binds on earth may be bound not in one heaven but in them all, as compared with the many who bind on earth and loose on earth, so that these things are bound and loosed not in [all] the heavens, as in the case of Peter, but in one only; for they do not reach so high a stage with power as Peter to bind and loose in all the heavens" (Commentary on Matthew 13:31 [A.D. 248]).
Cyprian of Carthage
"The Lord says to Peter: 'I say to you,' he says, 'that you are Peter, and upon this rock I will build my Church' . . . On him [Peter] he builds the Church, and to him he gives the command to feed the sheep [John 21:17], and although he assigns a like power to all the apostles, yet he founded a single chair [cathedra], and he established by his own authority a source and an intrinsic reason for that unity. Indeed, the others were that also which Peter was [i.e., apostles], but a primacy is given to Peter, whereby it is made clear that there is but one Church and one chair. So too, all [the apostles] are shepherds, and the flock is shown to be one, fed by all the apostles in single-minded accord. If someone does not hold fast to this unity of Peter, can he imagine that he still holds the faith? If he [should] desert the chair of Peter upon whom the Church was built, can he still be confident that he is in the Church?" (The Unity of the Catholic Church 4; 1st edition [A.D. 251]).
Cyril of Jerusalem
"The Lord is loving toward men, swift to pardon but slow to punish. Let no man despair of his own salvation. Peter, the first and foremost of the apostles, denied the Lord three times before a little servant girl, but he repented and wept bitterly" (Catechetical Lectures 2:19 [A.D. 350]).
Cyril of Jerusalem
"[Simon Magus] so deceived the city of Rome that Claudius erected a statue of him . . .While the error was extending itself, Peter and Paul arrived, a noble pair and the rulers of the Church, and they set the error aright. . . . [T]hey launched the weapon of their like-mindedness in prayer against the Magus, and struck him down to earth. It was marvelous enough, and yet no marvel at all, for Peter was there--he that carries about the keys of heaven [Matt. 16:19]" (ibid., 6:14).
Cyril of Jerusalem
"In the power of the same Holy Spirit, Peter, both the chief of the apostles and the keeper of the keys of the kingdom of heaven, in the name of Christ healed Aeneas the paralytic at Lydda, which is now called Diospolis" [Acts 9:32-34] (ibid., 17:27).
Ephraim the Syrian
"[Jesus said:] Simon, my follower, I have made you the foundation of the holy Church. I betimes called you Peter, because you will support all its buildings. You are the inspector of those who will build on Earth a Church for me. If they should wish to build what is false, you, the foundation, will condemn them. You are the head of the fountain from which my teaching flows; you are the chief of my disciples. Through you I will give drink to all peoples. Yours is that life-giving sweetness which I dispense. I have chosen you to be, as it were, the first-born in my institution so that, as the heir, you may be executor of my treasures. I have given you the keys of my kingdom. Behold, I have given you authority over all my treasures" (Homilies 4:1 [A.D. 351]).
Ambrose of Milan
"[Christ] made answer: 'You are Peter, and upon this rock will I build my Church . . .' Could he not, then, strengthen the faith of the man to whom, acting on his own authority, he gave the kingdom, whom he called the rock, thereby declaring him to be the foundation of the Church [Matt. 16:18]?" (The Faith 4:5 [A.D. 379]).
Pope Damasus I
"Likewise it is decreed . . . that it ought to be announced that . . . the holy Roman Church has been placed at the forefront not by the conciliar decisions of other churches, but has received the primacy by the evangelic voice of our Lord and Savior, who says: 'You are Peter, and upon this rock I will build my Church, and the gates of hell will not prevail against it; and I will give to you the keys of the kingdom of heaven . . . ' [Matt. 16:18-19]. The first see, therefore, is that of Peter the apostle, that of the Roman Church, which has neither stain nor blemish nor anything like it" (Decree of Damasus 3 [A.D. 382]).
Jerome
"'But,' you [Jovinian] will say, 'it was on Peter that the Church was founded' [Matt. 16:18]. Well . . . one among the twelve is chosen to be their head in order to remove any occasion for division" (Against Jovinian 1:26 [A.D. 393]).
Jerome
"Simon Peter, the son of John, from the village of Bethsaida in the province of Galilee, brother of Andrew the apostle, and himself chief of the apostles, after having been bishop of the church of Antioch and having preached to the Dispersion . . . pushed on to Rome in the second year of Claudius to over-throw Simon Magus, and held the sacerdotal chair there for twenty-five years until the last, that is the fourteenth, year of Nero. At his hands he received the crown of martyrdom being nailed to the cross with his head towards the ground and his feet raised on high, asserting that he was unworthy to be crucified in the same manner as his Lord" (Lives of Illustrious Men 1 [A.D. 396]).
Pope Innocent I
"In seeking the things of God . . . you have acknowledged that judgment is to be referred to us [the pope], and have shown that you know that is owed to the Apostolic See [Rome], if all of us placed in this position are to desire to follow the Apostle himself [Peter] from whom the episcopate itself and the total authority of this name have emerged"
(Letters 29:1 [A.D. 408]).
"Among these [apostles] Peter alone almost everywhere deserved to represent the whole Church. Because of that representation of the Church, which only he bore, he deserved to hear 'I will give to you the keys of the kingdom of heaven" (Sermons 295:2 [A.D. 411]).
Augustine
"Some things are said which seem to relate especially to the apostle Peter, and yet are not clear in their meaning unless referred to the Church, which he is acknowledged to have represented in a figure on account of the primacy which he bore among the disciples. Such is 'I will give unto you the keys of the kingdom of heaven,' and other similar passages. In the same way, Judas represents those Jews who were Christ's enemies" (Commentary on Psalm 108 1 [A.D. 415])
Augustine
"Who is ignorant that the first of the apostles is the most blessed Peter?" (Commentary on John 56:1 [A.D. 416]).
Council of Ephesus
"Philip, presbyter and legate of [Pope Celestine I] said: 'We offer our thanks to the holy and venerable synod, that when the writings of our holy and blessed pope had been read to you . . . you joined yourselves to the holy head also by your holy acclamations. For your blessedness is not ignorant that the head of the whole faith, the head of the Apostles, is blessed Peter the Apostle'" (Acts of the Council, session 2 [A.D. 431]).
Council of Effuses
"Philip, the presbyter and legate of the Apostolic See [Rome] said: 'There is no doubt, and in fact it has been known in all ages, that the holy and most blessed Peter, prince and head of the Apostles, pillar of the faith, and foundation of the Catholic Church, received the keys of the kingdom from our Lord Jesus Christ, the Savior and Redeemer of the human race, and that to him was given the power of loosing and binding sins: who down even to today and forever both lives and judges in his successors'" (ibid., session 3).
Pope Leo I
"Our Lord Jesus Christ . . . has placed the principal charge on the blessed Peter, chief of all the apostles, and from him as from the head wishes his gifts to flow to all the body, so that anyone who dares to secede from Peter's solid rock may understand that he has no part or lot in the divine mystery. He wished him who had been received into partnership in his undivided unity to be named what he himself was, when he said: 'You are Peter, and upon this rock I will build my Church' [Matt. 16:18], that the building of the eternal temple might rest on Peter's solid rock, strengthening his Church so surely that neither could human rashness assail it nor the gates of hell prevail against it" (Letters 10:1 [A.D. 445).
Pope Leo I
"Our Lord Jesus Christ . . . established the worship belonging to the divine [Christian] religion . . . But the Lord desired that the sacrament of this gift should pertain to all the apostles in such a way that it might be found principally in the most blessed Peter, the highest of all the apostles. And he wanted his gifts to flow into the entire body from Peter himself, as if from the head, in such a way that anyone who had dared to separate himself from the solidarity of Peter would realize that he was himself no longer a sharer in the divine mystery" (ibid., 10:2-3).
Pope Leo I
"Although bishops have a common dignity, they are not all of the same rank. Even among the most blessed apostles, though they were alike in honor, there was a certain distinction of power. All were equal in being chosen, but it was given to one to be preeminent over the others. . . the care of the universal Church would converge in the one See of Peter, and nothing should ever be at odds with this head" (ibid., 14:11).
Pope Leo I
"The blessed Peter persevering in the strength of the Rock, which he has received, has not abandoned the helm of the Church, which he understood. ( He is still with us) For he was ordained before the rest in such a way that from his being called the rock, from his being pronounced the foundation, from his being constituted the doorkeeper of the kingdom of heaven, from his being set as the umpire to bind and loose, whose judgments shall retain their validity in heaven, from all these mystical titles we might know the nature of his association with Christ" (Sermons 3:2-3 [A.D. 450]).
Peter is still with us in the person of the Pope,
the Vicar of Christ.