Reuben is a pig-like character who has appeared in 5 episodes total though only 3 of those as an actual antagonist. In the Party Cruise, he tricked Mung Daal, Chowder and Shnitzel into boarding a ship which he stole. He was the cooking instructor in Certifrycation Class. He tricked the gang into being his servants by planting his rat friend in his sandwich in The Rat Sandwich. He also made a brief appearance in Grubble Gum buying screams. He apparently dislikes Mung Daal. The feeling is mutual. He is a major antagonist of the show. Reuben is voiced by Paul Reubens, who also voices Ivor in Minecraft: Story Mode.
Grubble Gum - Reuben makes his first Cameo Appearance.
Certifrycation Class - Reuben is the teacher of that class and constantly gives Mung Daal Thumbs Down. While berating Mung Daal for not following the recipe's he give Reuben also berates for following his sandwich recipe which had mayo since he is allergic yet never informed anyone of this allergy.
The Rat Sandwich - After getting banned from the farmers' market by the Angry Rhino that owns the place, Reuben used the Rat on his sandwich to force Mung Daal's company into giving him free food or else he'd shut down the business by claiming they had a rat problem. Even as his partner, the Rat, tries to sneak in a bite of the food Reuben eats it before he has the chance despite them working together to get both them free food. In the end the Rat is caught only for Reuben to berate him and then use a whistle so a swarm of rats come in claiming now Mug Daal will have to feed him forever. Just as it looks like Reuben has won all the rats turn on him for never sharing any food to the point they are starving. As Reuben is forced out of the company he says the rats are no longer his friends.
The Party Cruise - Reuben stole the ship and he ruined Mung Daal's Vacation. When Mung Daal found out it wasn't Reuben's Ship, The Two Founders found the ship. Reuben makes a run for it on a paddle boat then he gets eaten by a giant fish. His Last words were, "Well. I don't like this one bit."
A Little Bit of Pizzazz - Reuben makes his second Cameo Appearance and its also his final appearance in the series.
Grim Adventures of Billy & Mandy