These characters (Baron Raymondo, Marquis (de la) Montalban, and Colonel Mendoza), appear in different situations, the first two during the family quest, and the third while romancing with daughters.
Baron Raymondo[]
He appears multiple times in the game, and defeating him is essential in completing the lost family quest. After retrieving all map pieces to the quests, he no longer appears, or becomes mentioned in the game. He uses a War Galleon in game, carrying 3000 gold. An error in the iPad version can cause his ship to respawn as "Evil Spaniard EVIL!" instead "Baron Raymondo EVIL!" after defeating him. This "Evil Spaniard" wears the same uniform as a Spanish Sloop of War captain, with a morion and breastplate.
Marquis Montalban[]
Must be defeated a few times in order to locate his hideout, which, after a land battle, causes you to duel with him, and if successful, ends the lost relatives quest. He is easily the best swordsman in the game, and, if the duel with him is lost, he'll escape, prompting you to have to hunt him down; he uses a Flag Galleon in-game with 5,000 Gold. In the iPad version one does not have to hunt Montalban down by ship if you fail. Succeeding at catching Montalban in his hideout earns you a massive 100,000 Gold, all the specialists for your ship, and Montalban himself as a crew member.
Colonel Mendoza[]
Captures the governor's daughter during the "romance quest". Appears to be identical to Raymondo, except that Raymondo has a black moustache and hair, whilst Mendoza's hair and moustache are grey. He uses a Fast Galleon in-game. Note that his motivation for capturing the governor's daughter is never stated, though it could be possible that the daughter's ex-fiance or Marquis Montalban hired him to spite the player. His ships carries 2000 gold.