"That is a decision you will soon come to regret. But you shall not do so for long...For I shall rend you asunder and devour your innards before you realize you are dead!"
Baramos and his forces menaced the world for an unknown number of years prior, which necessitated The Hero Ortega departing from Aliahan to slay him in the game's opening prolog. Though the king of Aliahan states that the world at large is unaware of the fiend's activities, his very presence emboldens monsters the world over to assault human settlements.
Throughout the first half of III Baramos is believed to be the final boss, but this is malicious facade; when The Hero defeats Baramos and returns to Aliahan triumphant, Zoma interrupts the celebrations to reveal Baramos was just an underling of his--an advance force to clear the way for his master. Having failed, Zoma announces that he will personally plunge the world into eternal darkness, causing The Hero to continue his quest.
Baramos will attack the party twice more in Zoma's Citadel, both as a ghost and a shambling corpse. There is no dialogue prior or during these encounters, implying that Baramos is not truly "revived" and is forced into further servitude by Zoma's magic. In the Dragon Quest III: The Seeds of Salvation remakes, a common enemy in Cloudsgate Citadel is a pallete-swap known as a Baramonster. Whether the baramonsters were in Zoma's employ is not certain.
Baramos appears as a Legacy Boss, obtained after completing Quest #062. He is the weakest of the Legacy bosses, but he is still very powerful and capable of casting Kafrizz and Kaboom and can also use fire breath and regular attacks (which are prone to inflicting critical hits). Ice attacks are his weakness, but he resists wind attacks.
Baramos returns as a boss battle in his castle, accessible from the last III chapter in the Echo Chamber. Due to the death of the Necrogondolier before the minion's revival ceremony could be completed, the fiend pulled himself back from the void by consuming souls and anguish.
Baramos appears as the boss of the Gate of Mastermind. He then talks to you and makes a odd threat of eating your guts so you will never be brought back to life.