Squealer is a character in Animal Farm by George Orwell, a pig who serves as the main minion of Napoleon and the tertiary antagonist turned anti-hero. Squealer goes around telling lies to the other gullible farm animals to cover up and or/justify Napoleon's atrocities and convince the animals to stay loyal to him. He represents the propaganda in the Soviet Union during the Stalin era, most likely Molotov, although in this case all of Squealer's claims are simply outright lies.
Squealer is described as being very persuasive and good with words, and the logic behind many of his "arguments" is that the only alternative to listening to Napoleon would be to bring back the old farmer, Mr. Jones, who even if Napoleon is not perfect must surely be far worse (in reality, Jones is almost benevolent by comparison), and that anything selfish the pigs might be doing is necessary to keep the farm from falling back under human control. Squealer also makes up false statistics claiming that the farm's productivity is always improving, and constantly tells the animals that all their hard work will pay off for them eventually.
Around the middle of the book, Napoleon and Squealer start altering the sacred seven commandments of "Animalism" to serve their selfish interests, and Squealer insists that the commandments have always been that way, and their memories are mistaken. By the end, they simply replace the commandments altogether with the self-contradictory statement: "All animals are equal, but some animals are more equal than others."
Squealer also practices "historical revisionism" by slandering Snowball, who was violently driven out of the farm by Napoleon's dogs. At first, he says that Snowball was simply being a poor leader, then claims that he was conspiring with Mr. Jones, and then goes as far as to say that Snowball had actually been fighting on Jones' side and was their enemy from the start, while in reality Snowball was the only pig with any remotely honest intentions.