Bowser is a fat dragon-like Koopa who is usually Mario's arch-nemesis. In the earlier videos, Bowser was usually one of the main antagonists of the bloopers (besides SMG3), but overtime, he reformed and became Mario's friend, although he has since still had villainous roles. He is the leader and king of the Koopa Troop army. Like Toad, Wario, and Waluigi, Bowser has seen a decrease in appearances in the ninth season.
He is one of two main characters in the Cooking With Bowser And Mario series, the other being Mario himself.
His main goals include capturing Peach Toadstool and trying to conquer the world, although his plans almost always failed, and he often needs the help of SMG3.
In more recent videos, Bowser is much less evil and behaves similar to (but not in the same extent) Mario and is obsessed with swag.
He once hosted a tech channel, but he eventually got bored with it and decided to make it a tech destruction channel instead, which resulted in it being banned by Youtube.
He was one of the many people infected by the T-Pose Virus that Waluigi created, who was later reverted back to normal.
In the earlier episodes, Bowser was similar to his canon counterpart, persistently and repeatedly kidnapping Peach as well as opposing Mario. However, as the blooper series went on, Bowser began to like Mario, and much of his personality appears to influence Bowser, making him act in a rather silly and retarded way. While still trying to kidnap and/or win Peach’s heart, his motivations became much more silly and friendly around most other people, as he’s shown to get along with most people in Peach's Castle.
Like his canon counterpart, he is shown to care for his son Bowser Jr. His New Years' Resolution was to try to be a better father for him. However, he isn’t very good at taking care of his son, as shown when he destroyed the gaming system in rage and neglected Jr. over a bouncy house in SMG4: Stupid Mario World.
As in Nintendo canon, Bowser has the ability to breathe fire. He is also apparently a good racer, as he was able to outlast most of the other racers in Stupid Mario Kart. However, he was eventually killed by Mario when Fishy Boopkins spread banana peels across the track and his kart fell on top of him, and later by Link when he blew him into a pit of lava.
Oddly, his player characters in Mushroom and Morons was a medic.
Kidnapping: He has kidnapped Princess Peach countless times. He was also accused of kidnapping children, but he was actually innocent.
He can successfully copy Peach and Mario's voice.
He hates SMG3 unless it happens that he lives with him.
He's rarely the actual antagonist in bloopers, contrary to his true nature in Super Mario 64 and the Mario series in general. One notable exception is in Super Mario Interactive.
He is somehow able to fly without using his Koopa Copter.
The Adventures of Mario and Luigi mini-series is probably Bowser's biggest role as a antagonist with Bowser's appearance not being until the end of Ep. 2 after the defeat of his son, Bowser Jr., and the downfall of his airship as the "surprise" main antagonist after he takes over Peach's Castle to proclaim it as the new Bowser's Castle.