He was created as a response to demand from Kids WB executives to include additional characters on the show. His presence is sporadic as the writers of the show believed that including an additional character would ruin the chemistry between Pinky and The Brain, as they worked best as a comedy duo, and a third character would therefore be out of place and unnecessary to the plot. It also foreshadows Elmyra seemingly being forced into the show in the final season. He is an obvious parody of Larry, one of the Three Stooges they share similar hair styles, and like his human counterpart, he acts as a middle man between the Brain's intellect and Pinky's stupidity. There's also an original theme song for the group which has Larry's name hastily spliced into key parts of the show's normal theme for example, "They're Pinky and The Brain (and Larry), yes Pinky and The Brain (and Larry), one is a genius, the other's insane (and the other one's Larry)", with Larry singing the added portions. The recurring theme of the episode is the acknowledgment (or lack thereof) of Larry's existence, just like in real life, where Larry is deemed the most underrated of the Three Stooges. Absolutely no explanation is given for Larry's presence Pinky and the Brain act as if he has always been there, even though the viewer has never seen him before, which could be another reason why his existence is constantly being pointed out. His lines consisted mostly of greetings and reminders that he is a part of the episode. At the end of the episode, when the Brain realises that they don't actually need Larry, Larry decides to change his name to Art (a reference to Art Garfunkel, whose hair is similar to that of the Three Stooge's Larry) and start a new career as a folk singer, singing "The Smells of Loudness" (a parody of The Sounds of Silence) with Paul Simon. Just as the Brain declares that he and Pinky will continue to attempt to rule the world without Larry, they are almost immediately joined by a mouse named Zeppo (a parody of Zeppo of the Marx Brothers), and the episode's closing song splices in Zeppo's name like it did with Larry in the opening theme. Although never seen onscreen beyond the cameo appearance, Larry is referred to by both Pinky and the Brain in subsequent episodes. He is voiced by Billy West, using the same voice as Stimpy from The Ren & Stimpy Show.
He has green eyes, sort of like Brain's pinkish-red eyes or Pinky's light blue eyes. Larry has brown head hair over his ears.