|“||This isn't right! This episode was suppose to be about snake nerds! SNAKE NERDS!||„|
|~ Irwin as he gets taken away by the CIA.|
Irwin is the secondary tritagonist of the Grim Adventures of Billy & Mandy series. He is usually the coward of the group when they deal with supernatural creatures. Although he is a coward, he was shown to have a dark and sinister side of his personality.
- In the "Halls of Time" episode, he messed with his older brother Melvin's timeglass that controls his aging for picking on him. He later breaks the hourglass, erasing his brother from existence.
- In the "Secret Snake Club", he joins a macrame club and claims that he joined it for the girls. But he really wanted to joined so he could make macrame pot holders that he could sell so he could raise enough money to buy a space laser that can damage eye's retina, forcing everyone to wear glasses. At the end of the episode, he gets arrested by the CIA. It was never explained how he escaped their custody.
- In Scythe for Sale, he becomes the main antagonist of the episode when he steals Grim's scythe. Irwin uses the scythe to hypnotize Mandy into being his girlfriend, and later his wife in a forced wedding (knowing well that what he is doing is wrong), and creates chaos in Endsville. When Billy and Grim tried to obtain the scythe from Irwin, he refuses to give it back until Grim and Billy defeated him. Grim turned him into a sea critter as punishment.
- When his grandpa the Phaorah King Popen Loken comes to visit him, he offers Irwin a pyramid made for him. Irwin accepts the offer and believed it would impressed Mandy. Eventually he becomes power hungry and enslaves and brainwashes everyone in Endsville not caring if they remained under his control. Some fans considered this to be his Moral Event Horizon.
- One episode revealed that he was born bad and that he once ripped off a man's face when he complained about his whining.