Scientists are also typical characters. They play a crucial role in understanding the situation, whether it's the cause of the impending doom or finding a new habitable place. They might be astrophysicists looking for new planets or biologists trying to preserve life forms.
Leaders are another common type. They have to make tough decisions on who gets on the ark, how resources are distributed, and how to maintain order during the long journey or stay in the refuge. They could be military leaders with strong leadership skills or civilian leaders elected by the group.
There are often the survivors. These are the people who manage to get on the 'ark' - whether it's a spaceship or an underground bunker. They are usually resourceful, like engineers who can keep the ark running or doctors who can deal with medical issues.