Saint Monica was a resident of North Africa (modern day Libya or Tunisia I would guess) in the 4th century and the mother of St. Augustine. She is the patron saint of mothers and her feast day is August 27th. Her great achievements were her own conversion to Catholicism, the conversion of her husband, and that of her son Augustine. Apparently she had to keep after her son for 17 years after her own conversion before he became religious a year before her death. This makes her pretty important for putting one of the most significant leaders of the early church on his path to greatness.
If anyone is still wondering St. Barbara was also a 4th century saint. Her father, a Dioscorus, apparently had her killed for converting to Christianity. Then he was struck dead by lightning.
This took all of 7 minutes to look up. First I had to find a dictionary of saints, easily solved by google http://saints.catholic.org/stsindex.html
They both sound legendary to me, but then I am not religious anymore. So I am probably biased.