Ratbert is a minor character in Scott Adams’ comic strip, Dilbert.
Ratbert first appeared in 1990 and, as with Catbert, was not a planned addition to the cast. He began as a lab rat named XP-39C^2 (no reference intended to Windows XP) tested with non-lethal experiments as the scientist could only afford one rat (Adams: “It meant I didn’t have to draw a lot of rat “extras” standing around in the scene”). The rat becomes suspicious when the scientist feeds him copious amounts of macaroni and cheese, which he first put down to the scientist simply being a good host. The rat escapes and burrows his way into Dilbert’s home. Dilbert at first takes exception to “plague-carrying vermin” but the rat decides to stay anyway, renaming himself to Ratbert. With Dilbert and Dogbert as well, this is the first indication of the -bert pattern. It’s not until Christmas Day, 1993 that Dilbert finally accepts Ratbert into his family.
He’s stupid, gullible, happy and sickeningly saccharine. This provides an excellent contrast to the other Dilbert characters, and often Ratbert appears in strips where he provides the almost-Taoist “wake up call”: “Hey, do you know what’s funny? If the goal of life is to be happy, and you work all day whereas I have fun, that means I’m doing better than you!”
Nowadays, Dogbert (basically Adams’ authorial presence in the strip) often employs Ratbert with Dilbert’s Company With No Name. This includes being an intern (“How did people ever look busy without computers?”) and a high level manager, with a piece of liver strapped to his belly which, as you’ve all guessed, was his external brain pack.
My favourite Ratbert strip comes pre-Dilbert acceptance, back when his cuteness made you want to violently kill him:
Ratbert: “I’ve developed a plan to make you pity me and then welcome me into your family.”
Cut to Ratbert is standing in front of a toilet roll, with a little face drawn on. He has little q-tips for arms
Ratbert: “I built Timmy the Toilet Paper Man. Timmy will be my only friend. It will be so pathetic and heart-rending that you will have to love me.”
Cut to Ratbert standing in front of Dogbert, Timmy is only the cardboard tube.
Ratbert: “Dilbert seems to have very little respect for Timmy.”