Note: This is King Bowser Koopa from the games. You may be looking for King Morton Koopa, Sr., the father of the Koopalings, who appeared in the cartoons.
King Bowser Koopa is the main antagonist of the Super Mario Bros. series. He is the archenemy of Mario.
He has been overthrown by Mario and replaced by his brother Morton Koopa, Sr. on more than one occasion.
Early attempts at Success
Bowser Koopa is the rightful heir to the throne of the Koopas. At the dawn of the 21st century, he conspired with Goomboss to overthrow Princess Peach and become ruler of the Mushroom Kingdom. However, upon executing his plan in February of 2001, he was foiled by an Italian Plumber known simply as Mario who, along with his brother Luigi, was transported into the Mushroom Kingdom while working as a plumber in Brooklyn. Bowser was knocked into a pit of lava and killed (though it should be noted the Bowsers from castles one through seven were fakes).
About a week later, Bowser did exactly the same thing again, but this time he paid the programmers to make the game infuriating and genuinely not fun. Regardless, Mario still defeated him and knocked him into another pit of lava. It was soon after this that Mario had a fever dream in which a fuckwit frog named Wart attempted to take over the world, but this was a recreation of another game called Donkey Donkey Picnic.
After this, his brother Morton Koopa Sr. took over as King of the Koopas. After a multitude of defeats at the hands of Mario and Luigi (and sometimes Peach and the worthless Toad), Morton Koopa Sr. returned his authority as king to the newly revived Bowser. Bowser then kidnapped Morton's seven children known as the Koopalings: Ludwig Von Koopa, Roy Koopa, Lemmy Koopa, Wendy O. Koopa, Iggy Koopa, Morton Koopa Jr., and Larry Koopa. He forced them all to fight Mario aboard Morton Koopa Sr.'s air ships. Mario went on one of his most famous adventures, murdering the Koopalings along the way (the Koopalings were later revived by Magikoopas). The princess was once again saved, and upon his defeat, Bowser was overthrown by Morton Koopa Sr. once again, leading to the events in The Adventures of Super Mario Bros. 3 and Super Mario World cartoon, where the Koopalings went by their odd nicknames (and also Morton Koopa Jr. looked like a total weirdo for reasons never made available to the public).
Upon all of these failures, Morton Koopa Sr. was forced to hand over his rule to Bowser on August 7. Although Bowser had prepared for an epic battle, Morton gave up peacefully since he was already giving up on world domination anyway (rightfully so since Morton was so bad at it). That following October, Bowser and the Koopalings once again kidnapped Peach, holding her captive in Dinosaur World just north of the Mushroom Kingdom. They were subsequently defeated by Mario. At this time, Bowser decided to take a few months off.
Super Mario 64
In April of 2002, Bowser decided to execute a new plan of taking over Peach's castle and hiding the 120 Power Stars (the original versions of the Power Moons) from her castle in pocket dimensions that could only be accessed by traveling through paintings in the castle. Mario got inside and entered one of the only doors unlocked and began his journey through these pocket dimensions.
Super Mario Sunshine
In June, Bowser caught word that Mario was vacationing in Delfino Isle. Bowser soon hatched a plan to frame Mario for stealing the Shine Sprites that powered Delfino Isle not to mention the act of graffiti (a hanging offense to the Piantas of Delfino Isle). On a side note, Delfino Isle was once on bad terms with the Mushroom Kingdom for infringing on the patent for Power Stars. This adventure of Mario's was among the first times that Bowser's son Bowser Jr. confronted Mario. Bowser Jr. was actually the one to kidnap Princess Peach this time because he thought Peach was his mother (though it's never been confirmed who Bowser Jr.'s real mother was). Soon enough, however, Bowser was defeated by Mario once again. Bowser decided to retire for an entire year after this defeat.
New Super Mario Bros.
In March 2003, Bowser Jr. kidnapped Peach again, and Bowser actually served as the first boss. Mario got behind Bowser, flipped a switch, and watched as Bowser got his skin melted off by lava, killing him. Towards the end of the game, Bowser was revived as a skeleton known as Dry Bowser, but was still defeated by Mario. By the end of the adventure, Bowser Jr. put Bowser's skeleton into a pot, reviving the Koopa King and making him much larger. Mario defeated the father-son duo nonetheless and saved Princess Peach.
In late April of that same year, Bowser and his son came up with a new plan. The seven Koopalings hid in a giant cake and delivered it to the castle during Princess Peach's birthday celebration on May 3rd. This actually worked, but Mario soon took chase. Mario went on to once again murder Morton Koopa Sr.'s seven children. Larry Koopa was mauled by wolves after his defeat. Roy Koopa died of heat exhaustion in the Desert. Lemmy Koopa froze to death in the snow. Wendy O. Koopa was knocked unconscious and subsequently drowned. Iggy was mauled by chain chomps, and Morton Koopa Sr. fell head-first onto solid rock. Ludwig Von Koopa was the only Koopaling (not counting Bowser Jr.) to survive after both his encounters with Mario. A certain Magikoopa managed to help each of the Koopalings in their respective second encounter with the plumber that day, but this only slowed down Mario at best. Mario defeated Bowser, but the Magikoopa cast a spell to make Bowser giant and immune to lava. However, Mario still managed to find a way to defeat Bowser using a switch that Bowser was dumb enough to leave in his castle. Mario had saved Princess Peach yet again.
Super Mario Odyssey
In July 2003, Bowser kidnapped Princess Peach and planned a wedding for the two (which probably qualifies as human trafficking, though Bowser gave himself diplomatic immunity beforehand). Mario was actually defeated this time, but the plumber soon found himself in the pillaged Hat Kingdom where he teamed up with Cappie, a sentient hat capable of possessing people like ghosts. Mario and Cappie traveled the world to finally put a stop to Bowser and his wedding on the Moon.
Mario's Stupid Adventures in Space
Bowser later decided that he was thinking too small, so he attempted to conquer the universe (because conquering The Mushroom Kingdom was working so well). In September of that year, he kidnapped Peach and took her into space. Mario tried to stop him but was knocked off into the depths of space where he soon met Rosalina. Mario soon found out that in order to stop Bowser, he would have to gather real Power Stars (the ones in the Mushroom Kingdom were Power Moons made to look like Power Stars) and Grand Stars (basically bigger, more powerful Power Stars) from across Space. After collecting enough, Mario eventually defeated Bowser in the center of the universe. However, Bowser screwed up so badly that he almost caused the whole place to collapse into a cosmic anomaly. Some members of the Luma species sacrificed themselves to save Mario who due to the event, started tripping balls about reincarnation of stars and the rebirth of the universe and also a gigantic Rosalina. Mario later woke up in the Mushroom Kingdom.
Bowser arrived back home in August of 2004. Bowser began plotting a new way to conquer the universe shortly thereafter. Bowser soon plundered a round space station with its own gravity for their power stars and grand stars. Soon, while Bowser was drunk, one of the Hammer Bros dared him to eat a Grand Star, which resulted in Bowser growing gargantuan. Bowser soon kidnapped Peach again and declared that he was going to have Peach bake a gigantic cake in the center of the universe. Soon enough, Mario found a way into space and eventually defeated Bowser in his giant form.
- Bowser, Bowser Jr., the Koopalings, and Morton Koopa Sr. are members of the elite Koopa species, which have evolved into a separate species from the soldiers known as the Koopa Troopas. The common ancestor of the two is believed to be the Kappa.
- The Magikoopas started off as regular Koopas who underwent some form of magic metamorphasis. Although they were not originally a part of Bowser's army, they were responsible for the creation of the Hammer Bros. who reproduce asexually.
- Interestingly, one version of the theory that YouTube Poop World is part of a simulation states that the Kappa were a mythological creature in the supposedly real country of Japan.
- Mario often calls Morton Koopa Sr. "Bowser" because he cannot tell that they are two separate entities, which might make him a racist.