Angels are God's messengers. We don't know what they look like, except that they appear as grand, awe-inspiring beings - not the chubby, children we see in pictures.
Angels appear in many places in the Bible, many times as messengers but the most familiar passages remind us of their role as protectors and comforters of God's people.
The angel of the LORD encamps all around those who fear Him, And delivers them. Psalms 34:7 (NKJV)
Because you have made the LORD, who is my refuge, Even the Most High, your dwelling place, No evil shall befall you, Nor shall any plague come near your dwelling; For He shall give His angels charge over you, To keep you in all your ways. In their hands they shall bear you up, Lest you dash your foot against a stone. Psalms 91:9-12 (NKJV)
Then the high priest rose up, and all those who were with him (which is the sect of the Sadducees), and they were filled with indignation, and laid their hands on the apostles and put them in the common prison. But at night an angel of the Lord opened the prison doors and brought them out, and said, Acts 5:17-19 (NKJV)
And when Herod was about to bring him out, that night Peter was sleeping, bound with two chains between two soldiers; and the guards before the door were keeping the prison. Now behold, an angel of the Lord stood by him, and a light shone in the prison; and he struck Peter on the side and raised him up, saying, "Arise quickly!" And his chains fell off his hands. Then the angel said to him, "Gird yourself and tie on your sandals"; and so he did. And he said to him, "Put on your garment and follow me." So he went out and followed him, and did not know that what was done by the angel was real, but thought he was seeing a vision. When they were past the first and the second guard posts, they came to the iron gate that leads to the city, which opened to them of its own accord; and they went out and went down one street, and immediately the angel departed from him. And when Peter had come to himself, he said, "Now I know for certain that the Lord has sent His angel, and has delivered me from the hand of Herod and from all the expectation of the Jewish people." Acts 12:6-11 (NKJV)
"Take heed that you do not despise one of these little ones, for I say to you that in heaven their angels always see the face of My Father who is in heaven. Matt 18:10 (NKJV)
"Also I say to you, whoever confesses Me before men, him the Son of Man also will confess before the angels of God. "But he who denies Me before men will be denied before the angels of God. Luke 12:8-9 (NKJV)
"Likewise, I say to you, there is joy in the presence of the angels of God over one sinner who repents." Luke 15:10 (NKJV)
"The Son of Man will send out His angels, and they will gather out of His kingdom all things that offend, and those who practice lawlessness, "and will cast them into the furnace of fire. There will be wailing and gnashing of teeth. "Then the righteous will shine forth as the sun in the kingdom of their Father. He who has ears to hear, let him hear! Matt 13:41-43 (NKJV)
"Then the sign of the Son of Man will appear in heaven, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of heaven with power and great glory. "And He will send His angels with a great sound of a trumpet, and they will gather together His elect from the four winds, from one end of heaven to the other. Matt 24:30-31 (NKJV)
For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord. Therefore comfort one another with these words. 1 Thessalonians 4:16-18 (NKJV)