Old Testament references

Cherubim at entrance to Garden of Eden, Genesis 3:24
Appear to Abraham, Genesis 18:1-33
Saved Lot and his family, Genesis 19:1-22
Intervened with Isaac, Genesis 22:11-18
Heavenly vision of Jacob's Ladder, Genesis 28:12
Accompanied Israel through the desert, Exodus 23:20 And Numbers 20:16

Aided the prophets

Isaiah 6:2-7
Ezekiel 1:4-28
Daniel 7:9-10
Zechariah 1:9-19

New Testament references

Appeared in connection with birth of Christ

Matthew 1:20
Luke 1:26-38

Appear to:

Paul, Acts 27:23
Peter, Acts 12:7-11
Cornelius, Acts 10:3-6
Sadducees didn't believe in angels, Acts 23:8
12 Legions of Angels, Matthew 26:53

Mentioned by name:

Raphael, Tobit 12:15
Michael, Daniel 10:13
Revelation, 12:7
Gabriel, Daniel 8:16
Luke 1:19

Fall of the angels

Deuteronomy 32:17
2 Peter 2:4
Jude 1:6
Revelation 12:7-9