Greg Dog

Grogopolis Barkery Dog was a villainous yet stupid dog that aimed to wipe out cats and, later, the multiverse.

Meeting lifelong enemies
When Greg started high school at Pezawoof High School, bullies forced him to wear a purple coat, although he turned out to like it and constantly wore it. On the evening of the talent show, Greg befriended Bubby Kristy and Doccy Zeus, and sometime after that began dating Bubby. Seeing as Doccy was Bubby's friend too, Doccy became jealous. Greg witnessed Doccy throw a flower at Bubby, and she swallowed it and went to hospital, ending Greg and Doccy's friendship. A few days later, Greg dragged Doccy into an abandoned factory and tried to kill him, but Bubby (who had developed supernatural powers) saved Doccy and defeated Greg, whose parents abandoned him and he was left homeless. This drove him insane.

Homelessness
While Greg was homeless, two travelers Smokey Alfie and Ewan Ome met him and gave him (little) money. Greg was going to test his dark powers on them, but decided to test them on "a sibling of one of them". Ewan was an only child, so Lex Alfie, Smokey's little brother, became the victim. Subsequently, Lex was cursed so that he could only have one beloved family member at a time.

Return to villany
In 2014, Greg found a lot of money, but spent it all on building a rocket and time machine. He used the rocket's ray to grab an unlucky citizen to torture, and he coincidentally captured Doccy. Bubby soon learnt of this and flew into space to save Doccy in Greg's rocket. The rocket was destroyed, but Bubby saved Doccy and Greg.

Greg was granted access to the fourth dimension by Apalala, where he got the atmospheric energy to make a time machine.

Greg used his time machine to transport Lex and his friend to the Cretaceous.

Doccy invented the T.M., his own time machine. Bubby used it, summoning a parallel Bubby named Kristy and another Greg. They went to the time when Greg had his ship in space, and another Greg attacked. However, all alternative characters returned to their own time.

Greg went shopping, and was unintentionally dragged into a fight between Bubby and an evil clone of her, Evil Bubby. Greg helped Bubby and Doccy destroy Evil Bubby and her slave clones.

At Christmas 2014, Greg constructed a killer robot, the RoboReaper. It attacked a tower/restaurant, and Doccy tried to stop it, but failed. Santa Claus arrived and destroyed the robot.

Unfinished

Soon after, Smokey and Ewan stole Greg's time machine for fun. They couldn't figure out how to work it though. Greg, determined to destroy all cats, kidnapped Ewan and Smokey (as well as a few other cats), and caged them on Greg's Home Island.

Travelling to the multiverse
At some point, Greg used his time machine and travelled to before the Big Bang, and survived (extremely rarely). Greg quickly collected some of the atmosphere in an enclosed space and time travelled back home before imploding. He used the atmosphere to construct a device that was able to travel through dimensions.

Trivia

 * Greg is allergic to cherries.