Gargoyles can be traced all the way back to ancient Egypt, but only came to prominence in Europe during medieval times when artistic architecture became commonplace. Gargoyles vary more than other monsters in physiology, but all varieties have rock-like skin and are bipedal, and the vast majority has wings.
Gargoyles have adapted a 'stone form' in which their body hardens further and takes on all the apparent characteristics of a simple statue. This allows them to inhabit even heavily populated human settlements without being discovered. It is only recently that gargoyles have started taking on human form and tried living among humans properly, and opinions are split over whether or not the current state of affairs is an improvement.
Despite what certain human cartoons have to say on the topic, a gargoyle's stone form isn't a debilitating condition caused by sunlight, but a natural defense mechanism that they can activate at will. However, gargoyles have excellent night vision and aren't very stealthy creatures when active, so the vast majority are nocturnal.
In battle gargoyles don't have much as far as special abilities, but they have fearsome strength and their skin is rock-hard even when not in statue form. They're also surprisingly agile considering their weight, both in the air and on the ground, and are feared by most other flying monsters. In general gargoyles aren't too aggressive, as sharing living space with humans for centuries has bred out most of the territorial instincts that many other monsters suffer from. Still, they DO have the short temper that many other monsters suffer from, so try not to get on their bad side. If you do end up fighting one, you'll find that its body is impervious to all but the strongest attacks. Its wings, however, are surprisingly sensitive, and gargoyles hate being grounded.