Marina (Pirates of the Caribbean: On Stranger Tides)

Marina was a beautiful and deadly young mermaid who resided at Whitecap Bay. She was known to have had a relationship with Jack Sparrow.

Early life
Not much is known about Marina's early life. Marina was known as a typical mermaid with siren-like qualities, which made her a dangerous threat. At some point in her life, she had a brief relationship with Jack Sparrow. However, it probably did not end well.

Battle at Whitecap Bay
When the Queen Anne's Revenge arrived at Whitecap Bay, Blackbeard ordered his crew to make a trap for the mermaids, by sending them in the boats and using his own men as a living bait. When one of the crewmen named Scrum started to sing My Jolly Sailor Bold, the song attracted Tamara. When she came to Scrum's boat, she continued Scrum's song. Her singing attracted Marina and many more mermaids.

Marina and all the other mermaids began to attack the boats. The mermaids created havoc for the intruders, by gradually working up the chain and heading for Blackbeard's crew along with the rest of her kind. Blackbeard used the power of his sword to call his ship which launched it's Greek fire cannons, luring the mermaids towards them. As mass destruction was caused as Marina's kind fought back with Blackbeard's men, the explosion at the lighthouse was the most destructive, caused by Jack Sparrow, with its bright light scaring the mermaids away. At the end of the battle, Marina had a brief reunion with Jack—by giving him a big slap on his face. While a young mermaid named Syrena was captured by Blackbeard's men, Marina fled with the rest of her kind. Her further fate is unknown.

Personality
Marina was extremely beautiful but also extremely dangerous. She was seductive, using her beauty to attract men before dragging them into the water to their doom. However considering she once had a relationship with Jack Sparrow it is possible that she may not be as vicious as most mermaids. Their relationship ended badly but she may have had a soft spot for Jack considering he survived being attracted to her. Also when they were reunited, Marina merely slapped Jack instead of trying to drown him.