Dark Bowser is the Final Boss of Mario and Luigi Bowser's Inside Story. He was formed by the Dark Star, which had absorbed Bowser's DNA inside his body and copied all Bowser's abilities. However, after escaping Bowser's Body, Dark Bowser had no legs. It was completed when the Dark Fawful Bug went inside Dark Bowser.
Dark Bowser has all of Bowser's abilities along with a few of its own. He can breathe blue fire, inhale, punch and curl into a ball. He also can create a large boulder, toss it into the sky, and break it apart with a fireball, causing flaming rocks to fall from the sky. He can also entrap Bowser in a cage of black lightning and throw a large energy ball at him. When defeated, he is instantly revived by the Dark Fawful Bug and grows larger. He then throws a ball of dark enemies at Bowser, knocking him back and forcing him to fight the enemies to get to Dark Bowser he has 1000 Hp.Edit
Dark Bowser is far more malicious then the original bowser.