Bowser

“Because I know how it feels to be mistreated. I really do. Especially when I was the bad guy.” — Bowser, End of the Road
Bowser was a contestant on Total Drama Mushroom Island, Total Drama Mushroom Action, and Total Drama Mushroom World Tour. He also competed on the Total Drama Mushroom: Winter Special.

Personality
In earlier seasons, Bowser was abrasive, rude, and a proud villain. He would often start fights with people, which caused many to dislike him. In Total Drama Mushroom World Tour, his personality was completely changed and he became more of a hero. He formed a close friendship with Blooper, which ultimately led him to become a better person.

Total Drama Mushroom Island
Bowser made his first appearance in Total Drama Mushroom Island as a member of the Killer Mushrooms. He and Mario began an early rivalry and would constantly fight over Peach. He was a power player from the start and even won the first immunity challenge during the merge, voting out his archnemesis, Mario. His time was cut short after that, though--in the next episode, he was voted out for being a huge threat.

Total Drama Mushroom Action
Bowser returned for the second season as a member of the Killer Tanooki Leaves. He didn't last long and was the first one eliminated from his team after losing the tiebreaker against Mario.

Total Drama Mushroom World Tour
Bowser was one of the 20 selected to compete in Total Drama Mushroom World Tour. He started as the unofficial leader of the Mega Men. After voting out Mario early on, he and Peach almost got involved in a romantic relationship before she was eliminated. He formed alliances with Metal Mario and Wario, however, they didn't last long. He eventually made the merge and befriended Blooper in the final six. During the rest of the season, he was largely targeting by Pink Gold Peach and Toad, but still managed to be the ultimate winner.

Total Drama Mushroom: Winter Special
Bowser returned for the fourth time as a contestant on the Total Drama Mushroom: Winter Special. He once again claimed the role as leader of the Ice Flowers, and formed a close friendship with Daisy and Rosalina. He also started a rivalry with DK, which ended up with him getting the boot in fourth place. He returned in the finale where he was cheering on Rosalina.