Gargoyle

In architecture, a gargoyle is a carved stone grotesque, with a spout designed to convey water from a roof and away from the side of a building thereby preventing rainwater from running down masonry walls and eroding the mortar between. Architects often used multiple gargoyles on buildings to divide the flow of rainwater off the roof to minimize the potential damage from a rainstorm. A trough is often cut in the back of the gargoyle and rainwater typically exits through the open mouth.
[Wikipedia]