Fortitude

Fortitude measures your character's ability to stand up to massive physical punishment, such as poison, paralysis and instant death magic. Your Constitution modifier is added to your Fortitude saving throw.

Classes with high Fortitude Saving Throws are:

Arcane Archer
Barbarian
Battlerager
Bear Warrior
Champion of Toran
Champion of Vorax
Cleric
Druid
Dwarven Defender
Fighter
Monk
Paladin
Pale Master
Ranger
Red Dragon Disciple
Shifter
Spellsword
Undead Slayer
Unholy Champion of Corath
Unholy Champion of Pyrtechon