St. Raphael the Archangel is first mentioned in the Holy Scripture in the book of Tobias in which he says "I am the Angel Raphael, one of the seven who stand before the throne of God." He appears disguised in human form when he travels with Tobias.
There is a bible story which explains that the archangel healed the Earth when it was made impure by the sins of the fallen angels. This is referred to in the book of Enoch.
In artwork, he is often depicted holding a flask or staff, wearing a flowing robe and sandals, or is shown with Tobias. His symbol is a fish.
His feast day is celebrated on Oct. 24 and also on Sept. 29 with the Archangels Michael and Gabriel.
St. Raphael the Archangel is the patron saint against nightmares (I'm surprised it's not St. Gabriel the Archangel who appeared to the Virgin Mary). It is said that single women should wear the archangel on a pendant and they will find the right man.