Larry the Sandwich
Larry the Sandwich is a sentient sandwich.
Appearance
Larry looks like a standard white bread sandwich with some lettuce, except with little black legs much like Bill's. He also apparently has a 'bread mouth', with which he can use to communicate (in a heavy Jersey accent).
History
Larry was originally a drunken (not to mention stupid) human who summoned Alcor to ask him to 'make him a sandwich'. Dipper, having little patience for this sort of nonsense, turned him into a literal sandwich. Thus began the adventures of Larry the Sandwich.
At some point, he comes to the realization he actually likes being a sandwich more than he liked being human.
Larry doesn't decompose like a normal sandwich would. In effect, he's immortal, and unable to deteriorate by natural means. However, that doesn't mean he can't be killed.
Relationships
Dave the Lollipop
Dave is a lollipop that never stops screaming, and Larry's friend.