Bowser actually exists, and it can be found in real encyclopedias. You may read more about it on the following wiki(s):
Bowser SSB4

Bowser is the king of the Koopa Troop, and the main antagonist of the Super Mario series. He is known for his many evil schemes, most of which involve him kidnapping the Mushroom Kingdom's princess. When not attempting to conquer the Mushroom Kingdom, he often competes in the sporting events that his foes start.