Sacred Scripture mentions three angels by name: Michael, Gabriel and Raphael. In Catholic tradition, these three angels are called archangels, in the angelic hierarchy.
7 Now war arose in heaven, Michael and his angels fighting against the dragon; and the dragon and his angels fought, 8 but they were defeated and there was no longer any place for them in heaven. 9 And the great dragon was thrown down, that ancient serpent, who is called the Devil and Satan, the deceiver of the whole world--he was thrown down to the earth, and his angels were thrown down with him. (Rev 12:7-9)
St. Michael is mentioned twice in the OT: Dan 10:1-26 and Dan 12:1; that is, he is only mentioned by the prophet Daniel, and in the context of conflict. He is mentioned twice in the NT: once in Jude’s epistle (Jd 1:9) and once in Revelation, as quoted above. Jude’s comment is notoriously curious; Revelation’s quote is again in a context of conflict. It is because of these Scriptural texts that St. Michael is often described as a warrior who helps the Church in her defense against the powers of evil. The above quote takes place at the end of the world, but has been used to describe the dawn of time, when the angels were created and conflict between some of them and God occurred; St. Michael was then the leader of the angels who drove the demons into hell.
The name Michael means “who is like God?” He is the patron of soldiers, police, mariners, grocers, and doctors.
26 In the sixth month the angel Gabriel was sent from God to a city of Galilee named Nazareth, 27 to a virgin betrothed to a man whose name was Joseph, of the house of David; and the virgin's name was Mary. 28 And he came to her and said, "Hail, full of grace, the Lord is with you!" (Lk 1:26-28)
St. Gabriel is mentioned only in Daniel in the OT and Luke in the NT. In Daniel, Gabriel explains apocryphal visions to Daniel in 8:15-26 and 9:20-27. In Luke, Gabriel brings news to Mary as noted above, and to Zechariah, the father of St. John the Baptist (Lk 1:5-20). As Michael is seen as our defender in conflict, Gabriel is seen as God’s messenger. The name Gabriel means “God is my strength.” He is the patron of messengers, telecommunications workers, and postal workers.
15 I am Raphael, one of the seven holy angels who present the prayers of the saints and enter into the presence of the glory of the Holy One." 16 They were both alarmed; and they fell upon their faces, for they were afraid. 17 But he said to them, "Do not be afraid; you will be safe. But praise God for ever. 18 For I did not come as a favor on my part, but by the will of our God. Therefore praise him for ever. 19 All these days I merely appeared to you and did not eat or drink, but you were seeing a vision. 20 And now give thanks to God, for I am ascending to him who sent me. (Tob 12:15-20)
St. Raphael is mentioned only in the book of Tobit. He appears to Tobias as a man who helps Tobias in various ways, including the defeat of a demon. Tobias is not aware that he is an angel, until Raphael reveals himself in the above quote. The story in Tobit is very enjoyable and is worth your while to read in its entirety. The name Raphael means “God has healed.” He is the patron of travelers and of illnesses.
The quote from St. Raphael raises a curiosity: he is “one of the seven holy angels” in the presence of God. Then, who are the other six? According to our Faith, SS. Gabriel and Michael are among these seven. Then, who are the other four? Apocryphal works like the first book of Enoch offer more angelic names, however such is not Sacred Scripture and one should be skeptical. The teaching authority of the Church rejects knowledge of specific angels outside of Sacred Scripture; that is, only our three archangels have been revealed to us. (cf. Pope St. Zachary, Synod of Rome, 745 A.D.)
If we leave this question alone, we can learn much from the three holy archangels of Scripture. They help humankind with conflict, with learning from God, and with healing and help from God. That is, they are with God, and they help us. This is the paradigm of our desired relationship with God: To be united with the Lord, which leads us to help others.
Some angels are given proper names to denote the service they are empowered to perform. In that holy city, where perfect knowledge flows from the vision of almighty God, those who have no names may easily be known. But personal names are assigned to some, not because they could not be known with out them, but rather to denote their ministry when they came among us. Thus Michael means “Who is like God;” Gabriel means “The Strength of God;” and Raphael means “God’s Remedy.”
Whenever some act of wonderous power must be performed, Michael is sent, so that his action and his name may make it clear that no one can do what God does by his superior power… So too Gabriel, who is called God’s strength, was sent to Mary. He came to announce One who appeared as a humble man to quell the cosmic powers. Thus God’s strength announced the coming of the heavenly powers, mighty is battle. Raphael means, as I have said, God’s remedy, for when he touched Tobit;s eyes in order to cure him, he banished the darkness of his blindness. (St. Gregory the Great, Hom 34, 8-9: PL 76, 1250-1251)