Bowser

Bowser is the main antagonist of Super Mario Galaxy and its sequel Super Mario Galaxy 2.

He is a powerful Koopa eager for cosmic conquest and archenemy of the protagonist of both games, Mario.

Super Mario Galaxy
Prior to the events of Super Mario Galaxy, Bowser attacks Rosalina's Comet Observatory and steals all the Power Stars, as well as the Seven Grand Stars that power the observatory. Bowser then uses the power of these stars to unleash his entire fleet onto the cosmos and take over many galaxies, planning to construct a galaxy reactor powered by the Grand Stars to create his own galaxy at the center of the universe. He then kidnaps Peach during the Star Festival, using a UFO and several airships to uproot her castle and taking it to the center of the universe, where he wishes to rule the universe with Peach as his empress.

Mario, with the help of Rosalina, collects the Power Stars and Grand Stars and destroys much of the Koopa Troop. He encounters Bowser twice in his attempt to rescue Peach: once at Bowser's Star Reactor, and the second time at Bowser's Dark Matter Plant.

At the star reactor, before the player can reach him, Bowser attempts to stop Mario by destroying the staircase leading to him by breathing meteors at him. During battle, Bowser's attacks include stomping the ground, which creates a shock wave, and trying to ground pound Mario. However, if Bowser ground pounds on any of the glass spots on the arena, they will break, causing him to fall into the lava and run around aimlessly. Mario can then spin attack him, causing Bowser to spin around the planet inside his shell, much like a normal Koopa. When Mario does this again, he falls unconscious, only to recover seconds later. Bowser is defeated when this is done again.

At the dark matter plant, Bowser uses the same tactics as before, but can generate more shock waves and even has his own version of the spin attack, but can be defeated by using the same method as the first battle. Regardless of these drawbacks, Bowser remains confident in his victory and the follow-through of his main goal to construct his own galaxy.

Mario eventually battles Bowser at the almost-completed galaxy reactor. During the final battle, Bowser Jr. holds Peach captive in an airship while Mario fights Bowser on multiple planets. On the first planet, Bowser attacks by using his shock waves. He then curls into a ball of stone and rolls around the planet, with his head exposed to attack. On the second planet, Bowser's attacks include curling up into two combined shells and rolling around the planet, as well as fireballs. By hitting him with a rubbery bulb, Bowser is knocked onto his back and begins moving around the planet; he can then be defeated as normal. At this point, the gravity of the nearby sun then pulls them toward it, and they begin the actual final battle at the core of Bowser's soon-to-be galaxy. Bowser's attacks are simply improved tactics from the previous battles, meaning that he can once again be trumped by ground pounding the glass and burning himself, allowing Mario to spin attack him. The defeated Bowser then flies into into the magma of the sun.

Afterward, the final Grand Star frees itself from the galaxy reactor. However, the lack of the Grand Star causes the sun to collapse in on itself, resulting in the formation of a massive black hole that begins to devour the universe. Bowser, however, is on the surface of the sun, on a piece of rock, before it explodes. As the universe is being sucked inside, the Lumas head into the black hole, and destroy it from the inside. Bowser later awakens in Toad Town, near Mario and Peach.

Super Mario Galaxy 2
Bowser appears in Super Mario Galaxy 2, once again as the main antagonist. At the beginning of the game, he invades the Mushroom Kingdom again, but this time at a gigantic size, due to the power of the Power Stars that he stole earlier. He kidnaps Princess Peach and flees into space again, claiming to build a galactic empire to suit his new size and put its capital at the center of the universe. Additionally, he attacks and destroys Lubba's starship prior to the game, stealing all the ship's Power Stars.

Bowser is faced three times in the game. The fights take place on a spherical planetoid, where Bowser attempts to crush Mario with his fists, and by sending meteors crashing down. He also uses his Fire Breath. When using his fists, Bowser's hand gets stuck in the planetoid briefly, and any meteors on the battlefield at the time rise and turn yellow, allowing Mario to strike. After each battle, when Bowser is defeated, he coughs up a Grand Star, causing him to shrink back down to his normal size and fall to the ground. Each time, however, he is not discouraged and flees, telling Mario each time that his plan is too far along to stop.

The final battle at Bowser's Galaxy Generator has two phases. When Bowser is defeated once, Mario attempts to collect the Grand Star coughed up by Bowser, but the Koopa King reappears, eats the Grand Star, regains his gigantic size, and then the two fall into a vortex to fight again. Bowser advances on Mario as time passes, eventually allowing Bowser to attack with a punch. Mario pushes him back by ground-pounding the meteorites at him. After Mario defeats Bowser for the final time, Bowser is sucked into the vortex, and is not seen again until Mario, Peach, and the Toad Brigade return to their planet near the end of the credits, where it is shown that he has become smaller than normal, and is unconscious when he is first seen. Mario can jump on top of Bowser or spin him, waking him up and causing him to become angry.

Personnality
Bowser can be described as a brutal, serious, dark, ruthless and calm cosmic conqueror, in stark contrast to his older representations, which, while still dangerous, represented an impulsive, naive Bowser and constantly overtaken by Mario and his friends.

Thus, Bowser is a threat to the entire universe and an incredible tactician capable of overtaking Mario several times, first by lifting Peach Castle in the first game, then by continuing his plan despite his successive defeats against his archenemy until the final battle at the Heart of the Universe.

Most of Bowser's shots revolve around Princess Peach, as he kidnapped her twice at the beginning of both games. The reason for this is that he wants to make her his imperialist forever, but he doesn't seem to care about his well-being, by having her kept by Bowser Jr. in Mario Galaxy and by locking her in a bubble in Mario Galaxy 2.

Powers and abilities
As a hybrid of Koopa-dragon and Star Child, Bowser is an immensely powerful being capable of setting in motion the conquest of the entire Universe. He is also a great enemy for Mario, capable of confronting him on equal terms (although he systematically loses) and surviving a fall in a sun, although he was finally killed by the explosion of the Heart of the Universe; before being resurrected by Rosalina's time travel.
 * Fire breath: Bowser's main means of attack. He is able to breathe many fireballs (in Super Mario Galaxy) or a long stream of fire (in Super Mario Galaxy 2).
 * Superhuman strenght: In Super Mario Galaxy 2, Bowser showed superhuman strength, as he is able to create craters in a planet with a single punch.
 * Superhuman resistance: Bowser has an immense superhuman resistance, to the point that he is almost immortal. He was able to survive a fall in a sun, then a fall in a black hole in Super Mario Galaxy 2. However, he was unable to survive the explosion of the Heart of the Universe at the end of Super Mario Galaxy, and to be resurrected by Rosalina's time manipulation
 * Shell: Bowser is able to fit into his shell, making it invulnerable until he comes out of his shell, showed in final battle in Super Mario Galaxy.
 * Electrokinesis: Bowser has demonstrated vast electrokinetic powers. He was able to generate large amounts of electricity at the beginning of Super Mario Galaxy. During his duels with Mario, he also generates electric shock waves.
 * Geokinesis: Bowser is able to control the earth, as in the final battle with Mario in Super Mario Galaxy where he partially transforms himself into a stone ball.
 * Teleporting: Bowser is able to teleport, as he shows in both games by fleeing after his losses to Mario.
 * Tenebrokinesis: Bowser is able to manipulate dark energy for different effects, such as a spinning top attack with black energy in Super Mario Galaxy or surrounding his fist with black energy in Super Mario Galaxy 2.
 * Flight: In Super Mario Galaxy 2, Bowser showed himself capable of flying, first by fleeing the Mushroom Kingdom by air and then during his battles with Mario where he levitated.
 * Telekinesis: In both games, Bowser demonstrated that he could levitate Mario to take him to the battle arena.
 * Power Stars absorbtion: Bowser is able to absorb the energy of the Power Stars to increase his powers in Super Mario Galaxy 2.
 * Size-changing: By absorbing the energy of the Power Stars, Bowser is able to increase its size to an incredible giant level.
 * Meteors summonning: In Super Mario Galaxy 2, Bowser is able to summon meteors by simple roar.
 * Energy bubbles creation: Bowser was able to create a pink energy bubble to hold Peach back.
 * High intelligence: Bowser has shown himself to be a very intelligent conqueror and a formidable tactician, capable of almost conquering the entire Universe and surpassing Mario several times.

Trivia

 * Bowser's incarnation in Super Mario Galaxy marks his return as a dark and serious villain, where his previous incarnations described him as a comic villain.
 * The incarnation of Bowser in Super Mario Galaxy is probably the most powerful incarnation to date, given the large number of powers he has shown.