Clados Vader was a mysterious changeling entity who dwelled in the oceans of Iskalon. It was a giant deformed shark, and it could turn into the shape of the Sith Lord Darth Vader. In 0 ABY, Clados was killed by Luke Skywalker for having captured the golden droid C-3PO.
Clados Vader was a malevolent shapeshifter who lived on the oceanic world of Iskalon, in the Mid Rim Territories. It could assume the appearance of Darth Vader—hence the creature's name.
Shortly before the destruction of the first Death Star, Clados Vader took the protocol droid C-3PO hostage in an underwater chamber. Luke Skywalker came to rescue his friend and confronted the monster, who had metamorphosed into Lord Vader. One swipe of the Jedi apprentice's lightsaber and the fake Vader transformed back into its real form, an enormous shark-like creature with a pinkish hue. After the shapeshifter was defeated, Luke Skywalker and C-3PO set off to battle the Death Star.
Clados Vader was one of the stage bosses in the Japanese Star Wars 1987 video game. The game featured various fake Vaders which all happened to be shapeshifting monsters. The canonicity of this game and the creatures it features is dubious.
According to both "Game On!," an article published in Star Wars Insider 135, and the game manual, the fake Vaders (Clados, Gyaos, Sasori and Wampa) were "intended as illusions representing Luke's fears, like the Cave of Evil scene in Empire Strikes Back." However, since those game opponents were able to kidnap Luke Skywalker's allies and hold them prisoner, this article assumes they were real creatures rather than illusions. Additionally, the Vader-shaped figure that Skywalker fought in the Cave of Evil was more than mere illusion, being in fact a protean dark side entity known as the Dark Spirit.
In the original Japanese version, he was identified via katakana syllabary as クラドスベーダー (Kuradosu Beidā). While Beidā is a transliteration of "Vader" in Japanese, the element クラドス (kuradosu) derives from the Japanese name of shark genera, as examplified by the zoological names クラドセラケ (Cladoselache) and クラドダス (Cladodus).