All Paizo-official classes are available in Under the Dome. 3.X, third-party, and homebrew classes are allowed on a case-by-case basis. The following list details Pathfinder's core classes and their place within the dome.

Barbarian
Barbarians are quite common in the dome, with a great deal of them being counted among the leadership of the Outsiders. It is said that the leader of the Outsiders, the Highlander, possesses great and terrible powers when in the throes of a berserker rage.

Bard
Musicians, dancers, and other street performers are common in the more stable areas of the dome, though those with actual magical talent are rare. These individuals are highly prized among the ruling class of most factions, especially the Redstone Lords.

Cleric
The most widespread religion in the dome is known as the Children Beneath the Black. A vast majority of the dome's inhabitants were raised "beneath the black", though actual clerics of the religion are uncommon. The Rulers Beneath the Black is a theocratic faction within the dome whose leadership is made up of these holy men.

Technotopia is another theocracy dedicated to the worship of the "Past Gods", the pre-Collapse scientists and engineers who possessed sacred knowledge of technology lost to humanity through their sins.

A large number of small cults exist throughout the dome as well, worshiping obscure gods or upholding obtuse tenants.

Druid
Druids are exceedingly rare in the dome. The few that do exist are extremely valuable to the farmers who scrape meager crops from the dome's ancient greenspaces.

Fighter
Like in most other settings, fighers are among the most common classes under the dome. There is always someone looking to hire a sword-arm to visit violence upon their rivals.

Monk
Though true monastic orders are nearly unheard of in the dome, the occasional warrior skilled at unarmed and unarmored combat does make a name for themselves under the dome.

Paladin
Paladins are uncommon in the extreme, surpassed in rarity only by druids. The few that do exist typically count themselves as Children Beneath the Black.

Ranger
While true woodsmen are non-existent in the dome, rangers do find a place for themselves among the ruins, with urban-oriented rangers finding great success.

Rogue
Like fighters, rogues are very common. Thieves, vagabonds, and scavengers can find a place for themselves nearly anywhere in the dome.

Sorcerer
Wielders of natural arcane might, sorcerers are more common under the dome than in other settings. Many have mutations and strange technologies to thank for their abilities.

Wizard
While rare, wizards wield great power within the dome. The Comet Callers, a relatively new faction in the dome, is ruled entirely by those with arcane ability, and their hierarchy is organized by magical potency. It is also said that a secret cabal of wizards exists within the dome that has access both to powerful magics and wondrous pre-Collapse technologies.