Asking for a specific reason. Very curious as to the age of the Corps and what Green Lanterns would have possibly been around (although not on Earth) during the 18th Century?
Mogo has been an instrumental member of the Corps for a very long time. The rings don’t even work properly without him.
The Corps itself was formed 3 billion years ago, by general accounts.
Tyran’r of Tamaran, one of the first seven Green Lanterns, is still alive today.