Hall of Infinite Doors

The Plumber is somewhat of a staple in the Ratchet & Clank series. He always appears with his rear end sticking out whatever he is working on ("Look, plumber's crack", "Hey, I know those pants", and "Whoa, déjà vu!"). Insomniac Games brought back the 'mining' system from Going Commando into Up Your Arsenal, because the Plumber sets you a task in which if you find any Sewer Crystals in the Aquatos Sewers and bring them to him (they're fresh from the bowels of the King Ameboids), he'll "pay you for 'em in bolts", since he's making something special for the missus. Also, in Going Commando, he mentioned something along the lines of, "See you sometime next year..." He doesn't appear in Ratchet: Deadlocked because as the message at the end of the credits says, he was not able to appear in that game due to a "sump pump emergency in the Rygylian Nebula" he was assigned to. The Plumber appears, but does not speak, in part of a dream-state world within Ratchet & Clank: Size Matters.