Impostor Captain Tennille

"That's right, I'm not the real captain! I disposed of the real captain, and left him resting at the bottom of the ocean!"

- Impostor Captain Tenille

The Impostor Captain Tennille (偽キャプテン・テニール) is an unnamed tertiary antagonist featured in the third part of the JoJo's Bizarre Adventure series, Stardust Crusaders, specifically the "Dark Blue Moon" story arc.

He is an assassin sent by DIO who fights the Joestar Group in the middle of the ocean on their way to Egypt. He is a Stand user and wields Dark Blue Moon.

Appearance
The assassin appears as a tall, muscular man possibly in his late thirties. He has a fairly inconspicuous appearance as he only has a moustache and a soul patch for a facial trait and has a mere crew cut.

His attire is similarly ordinary as he wears a simple shirt and pants, complete with gloves, a plain kerchief tied around his neck, and a captain's cap.

Though the true Captain Tennille is never shown, one can assume that the impostor was practically identical to him, since his men, who had worked for ten years on the same ship, did not even suspect the replacement.

Personality
The assassin is foremost methodical, originally planning to separate the Joestar Group and eliminate them one by one. However his plan is immediately foiled by a fairly dull trick from Jotaro Kujo and he immediately dives into the water grabbing Anne hostage to bait the group. He is quite confident in Dark Blue Moon's abilities, and believes himself capable of taking on the whole group together once he's in the water. The impostor is also quite thorough in his work as he planted bombs on his ship to prevent the Joestar Group from sailing to Egypt.

When disguised as Tennille, he appears to be a fairly aloof and stern individual. His disguise seems to be meticulous as nobody on the ship noticed.

He seems to be fond of the ocean, as he confronts Jotaro for smoking and puts out the cigarette on his cap, asking if Jotaro was going to throw the ashes and the cigarette into the beautiful ocean.

Stand
The assassin's Stand is Dark Blue Moon, a considerably independent humanoid Stand of great advantage in water due to its ability to swim, create whirlpools, throw its razor scales as projectiles, and create barnacles that drain the strength of its foes.

Lung Capacity
The assassin's' lung capacity surpasses the human average by three times, and through practice, his personal record was 6 minutes and 12 seconds.

Background
The assassin is one of the Tarot Card representatives sent by Enya the Hag to kill the Joestar group. Seeing that the Joestar group decided to travel by sea after the attack of Gray Fly, he killed the real captain and took his place. He threw the captain into the ocean and boarded the ship with everyone else, no one noticing that he isn't the real Tennille. He planned to kill the group one by one while inside the ship.

The impostor at some point plants numerous bombs in the ship to stop Jotaro and company from reaching Egypt.

Stardust Crusaders (1988)
The impostor captain sails on the boat that the Joestar Group have taken to go from Hong Kong to Singapore. After Jotaro and Anne are attacked in the water by a mysterious creature, Jotaro has become suspicious of the crew members and believes one of them may be a Stand user.

The impostor appears after Jotaro climbs back onto the ship, berating Anne for sneaking on and then Jotaro for smoking on his ship. Jotaro quickly accuses him of being the Stand user. Although Joseph Joestar insists that the Speedwagon Foundation had checked his credentials, Jotaro decides to find out if he is the culprit anyway by playing a bluff on him: he says that breathing even a minimal quantity of smoke causes a big vein to appear on the nose of a Stand user. The impostor Captain Tennille immediately falls for it, and reveals his true identity and that he had killed the real Captain Tennille earlier. He tries to take Anne hostage, but before he manages to do so he is stopped by Star Platinum. The assassin, however, drags Jotaro underwater with his Stand Dark Blue Moon, where his Stand can fight at full power. He traps Jotaro into a vortex, attempting to slash him with Dark Blue Moon's razor scales. He even manages to create some sort of little Cirripede that can drain energy from his opponents' Stands.

Finally, by exploiting Star Platinum's ability to stretch his index and middle fingers, Jotaro stabs the enemy Stand and rips half of his head, defeating him. However the impostor's bombs suddenly go off in the ship, leaving the protagonists to encounter their next enemy Stand, Strength. The assassin, however, is assumedly left to die in the sea.

JoJo RPG (SFC)
The events from the Dark Blue Moon arc occur differently than in the original story, as the impostor Captain Tennille uses his Stand to attack the party within a water trap found in a building, instead of on a boat. Anne is completely removed from the game, resulting in the impostor Captain Tennille not using her as a hostage to attack the team.

JoJo's Bizarre Adventure (PS1)
Impostor Tennille or Captain Teneil in the English localization, appears as a Mini Game in Super Story Mode. His fight is simply a "quick time event" mini-game, where the player must dodge all the attacks from the impostor Captain Tennille's Stand. Imposter Captain Tennille's special battle can be unlocked in Book Mode.

Trivia

 * His name in the Crunchyroll and English dub versions is Captain Dragon, which still retains the Captain & Tennille namesake, as "Dragon" refers to one-half of the duo, Daryl Dragon, who is the Captain's real name.