Reuben Grinder (voiced by Nick Kroll) is the owner of the Edible Edibles Sandwiches sandwich shop. His name comes from two forms of sandwiches: the Reuben and the Grinder, which is a toasted hero sandwich.
He first appeared in the episode "Chuck Makes a Buck", where he was being robbed by Chuck the Evil Sandwich-Making Guy. Thanks to WordGirl, Reuben employed Chuck as the store's new spokesperson/mascot due to his sandwich face, and he became popular, even to the point of having balloons of him made and being mobbed wherever he went.
However, in a falling out at his store on sandwich making for the annual Fancy People's Annual Awards Dinner, Chuck quit and turned the floor of the ballroom into the bottom half of a sandwich in which Reginald states that "the upper crust [of the sandwich] is going to crush the upper crust [the fancy people]".
Later, in the episode "Chuck and Brent Ride Again", Chuck attempted to rob Reuben Grinder again, this time with his brother Brent as his "sidekick", but then Reuben and Brent went into business selling loaves of peanut butter bread and jelly bread.