Who are our Guardian Angels?
No evil shall befall you, nor shall affliction come near your 
tent, for to His Angels God has given command about you, that they guard you in 
all your ways. Upon their hands they will bear you up, lest you dash your foot 
against a stone.
Psalm 91: 10-12 A heavenly spirit assigned by God to watch over each of us 
during our lives. The doctrine of angels is part of the Church's tradition. The 
role of the guardian angel is both to guide us to good thoughts, works and 
words, and to preserve us from evil. Since the 17th century the Church has 
celebrated a feast honoring them in October throughout the Universal Church. 
Since the last calendar revision this feast is Oct 2. 
He has charged His angels with the ministry of watching and safeguarding every 
one of His creatures that behold not His face. Kingdoms have their angels 
assigned to them, and men have their angels; these latter it is to whom religion 
designates the Holy Guardian Angels. Our Lord says in the Gospel, "Beware lest 
ye scandalize any of these little ones, for their angels in heaven see the face 
of My Father." The existence of Guardian Angels, is, hence a dogma of the 
Christian faith: this being so, what ought not our respect be for that sure and 
holy intelligence that is ever present at our side; and how great our solicitude 
be, lest, by any act of ours, we offend those eyes which are ever bent upon us 
in all our ways!
Excerpt from: http://www.catholic.org/saints/angel.php