There are three known examples at present in the Gargoyles Universe: Fox, during the time that she had been transformed into a werefox by the Eye of Odin, and Fara Maku and Tea Gora, who were turned into werepanthers by Anansi (Wolf does not count as a were, because he achieved his present condition through genetic engineering rather than through magic, and because he has no ability to change shape). ("Eye of the Beholder", "Upgrade", "Mark of the Panther")
The nature and origins of weres vary on an individual basis, although magic always plays a part in their creation. Because of this great variety, few common factors exist, and fewer still have been revealed. In the episode "Ill Met By Moonlight", Katharine mentions that "vampires and weres" might be vulnerable to silver in the same way that Oberon's Children are vulnerable to wrought iron, although no were on the show ever displayed such a weakness, and Katharine may simply have been misinformed by Medieval superstition. Indeed, Greg Weisman has stated that the altered Fox and Wolf, and perhaps the werepanthers as well, lack this vulnerability.  Greg has also hinted that gargoyles might also be able to contract lycanthropy, although he has not gone into specifics. 
Real World Background
Legends about weres exist all over the world; werewolves are the best-known in Europe, but there are also stories about wereleopards, werefoxes, werejaguars, wereravens, weredeer, werehyenas, werebears, and even weresharks, among other animals. Weres are generally able to assume the form of whatever large predator the area is most familiar with. They are usually portrayed as malevolent beings, although this is not universal. In some stories the transformation is an involuntary result of a curse, while other legends tell of weres who use magic spells or innate abilities to change form at will. Sometimes a were can be identified in human form by certain marks on their bodies; for example, weresharks and werehyenas are both known to have an extra mouth in their human form, which they must conceal. In Japanese stories, weres are not transformed humans, but instead are animals who take a human shape.
- Were at Wikipedia, the Free Encyclopedia