Toa 95 did a good job cleaning the history section of the Kerog page awhile back, but the characterization stuff is still insanely bad.
When Bowser was developed, he was a typical villain of pure evil with immense hatred and anger. Cruel and ruthless, he is typically portrayed as a power-hungry tyrant who leads violent attacks that threaten the lives of hundreds. Bowser's ultimate goal is to conquer the Mushroom Kingdom, and eventually, the entire universe. His infamous plans and numerous crimes, ranging from simply kidnapping Princess Peach to acts of terrorism, have earned him a reputation feared by the entire Mushroom World. While this status of evil is still very prevalent in the series, a humorous tone has recently been added to his personality and is shown to be more complex in terms of his relationships with his rivals. [...]
While his lack of apparent common-sense is widely evident, Bowser has also been shown on many occasions to be highly intelligent. Many of his plans often make use of high-tech equipment and complicated machinery, designed and built by himself. In Mario Party Advance, when the player arrives at Bowser Lab, Bowser claims to have an IQ of 9,800. He has also shown himself to be quite adept at use of various magics, both innate and talisman-based. He often develops strategies in his conquest of the Mushroom Kingdom as well as defense against Mario, as evidenced by his division of power among his Koopalings and various generals to act as governors over conquered lands, which is a sign of an intelligent and compromising leader. [...]
Bowser's temperament has been depicted varying from pure, driven evil to a comical child-like villain. Despite this widely-opposing personality, any emotions other than anger or hatred have rarely been shown. Bowser has never been seen acting remorseful for his numerous atrocities and destruction, ranging from the localized Mushroom Kingdom to the outermost reaches of the universe. He also seems to lack a sense of empathy, which results in a disregard for any other life. In Paper Mario, Mario's defeat at the hands of Bowser, to which Bowser simply mockingly laughs at, is essentially murder before Mario is revived by the combined energy of the Star Spirits. Perhaps Bowser's most extreme disregard for other life is in Super Mario Galaxy, where his plot consists of wiping out entire galaxies to create a cosmos he can control.