Clan
Clan - A group of individuals with a common ancestry.
In the Gargoyles Universe, the word clan is most often associated with groups of gargoyles who defend a territory, including their rookery if present, and usually form a protectorate of some sort. However, Macbeth also referred to his people in ancient Scotland as 'Clan Moray'.
Ancient and Extinct Clans
We know of several clans that once existed, but have gone extinct. Goliath once said that at one point (probably while humans were still in the stone age) there were gargoyle clans all over the world. Gargoyles were probably the dominant species at that time, though it is unlikely their numbers equaled the current human population. It seems most, if not all, gargoyle clans were destroyed by humans one way or another. Following is a list of extinct clans. Keep in mind that as Goliath's comment indicates, this list is far from complete.
The Irish Clan - Ireland - Destroyed sometime between 10 AD and 1996.
The Wyvern Clan - Wyvern, Scotland - Destroyed in 994.
The Wyvern Clan (Split) - Scotland - A branch of the original Wyvern Clan. Destroyed between 988 and 1020.
Demona's Clan - Moray, Scotland - Destroyed in 1057.
The Scone Clan - Scone, Scotland - Destroyed by 1057 at the latest, and probably decades earlier.
The Olympian Clan - Olympus, Greece - Destroyed sometime before 1996, and probably centuries earlier.
Greg Weisman has also confirmed that in addition to this list, Norway once had at least one clan (which makes sense, given Odin's comment about not seeing many gargoyles in Norway in recent times), that the continent of Africa had at least one clan at some point. Grandmother made a mention of not seeing gargoyles in many generations, which could hint at extinct clans near the Western coast of North America, though she also said that in the past, gargoyles had never lived on Queen Florence Island. Other locations that Greg Weisman hints had clans are Italy, and more specifically Rome, Persia, and Egypt. Gargoyles from these and other Mediterranean locations may have gone on to join the clan on New Olympus that seems to have been founded mostly by members of the Olympian Clan. It also seems likely that ancient Camelot had a gargoyle clan since Arthur seemed to be very familiar with them. There were probably many other clans in Ireland, Scotland and Greece, besides the ones listed. Basically, as Goliath said, there were clans located all over the planet at one point. However, Greg Weisman has said that there were no gargoyle clans existing in Antarctica in ancient times, probably due to the climate and seasonal sunlight issues.
The Surviving Clans
In 1993, shortly before Goliath's Clan was awakened there only eight clans alive in the world. They are all quite old, and have managed to survive by hiding from humans, living in extremely remote locations, or forming solid bonds with human allies.
The London Clan - London, England
The Ishimura Clan - Ishimura, Japan
The Mayan Clan - ChacIxChel, Guatemala
The Korea Clan - Pukhan, Korea
The Xanadu Clan - Xanadu, China
The Loch Ness Clan - Loch Ness, Scotland
The New Olympian Clan - Mount Thanatos, New Olympus
The Avalon Clan - Oberon's Palace, Avalon
It is unclear which of these clans is the oldest, but the Avalon Clan is probably the youngest clan and the New Olympus Clan is likely the next youngest because it was founded from other clans that existed at the time. Greg Weisman usually lists the clans in this exact order, so it is possible that they are in order of how old they are (oldest to youngest), though that is merely speculation.
The First New Clans
Between 1994 and 1996, two new clans would be founded. One was awakened from a magic spell that left them sleeping for a thousand years, while the other was created through scientific cloning.
The Manhattan Clan - New York, U.S.A.
The Labyrinth Clan - New York, U.S.A
Future Clans
Sometime between 1996 and 2188, gargoyles from the ten existing clans (by 2188, collectively known as the Gargoyle Nation) will go on to form two new clans.
The Camelot Clan - New Camelot, Antarctica
The Wyvern Clan - Wyvern, Scotland
The Wyvern Clan will be very traditionalist and, in contrast, the Camelot Clan will be very internationalist.
After 2198, the Gargoyle Nation will create two new clans.
The Liberty Clan - Queen Florence Island, Canada
The Notre Dame Clan - Paris, France
As the years go by, one can assume that the gargoyle population will continue to climb and more clans will be formed, once again bringing about a time when gargoyle clans are throughout the world.