Screwy Squirrel (also known as Screwball Squirrel) is an animated cartoon character, an anthropomorphic squirrel created by Tex Avery for Metro-Goldwyn-Mayer.

Among some of the more outrageous cartoon characters, Screwy's feats include pulling objects out of thin air, doubling himself, and breaking the fourth wall, all the while uttering a characteristic cackling laugh. The character was not as successful as Avery's Droopy was at this time, appearing in only five cartoons: Screwball Squirrel (1944), Happy-Go-Nutty (1944), Big Heel-Watha (1944), The Screwy Truant (1945), and Lonesome Lenny (1946).

The character was known for being brash and erratic, with few sympathetic personality characteristics such as Bugs Bunny's nobility and Daffy Duck's pathos. Most of his cartoons had him paired with Meathead Dog (voiced by screenwriter Cal Howard in Screwball Squirrel, Tex Avery in Happy-Go-Nutty, and Pinto Colvig in The Screwy Truant) as his adversary. Meathead's physical appearance differed between the three shorts in which he appeared (with his ears changing color from grey-blue to black in Happy-Go-Nutty, and donning a new color palette in The Screwy Truant), but otherwise the character remained the same.

Screwy's shorts revolve around his infliction of various forms of torture on Meathead – or another enemy – for seven minutes, often doing so by breaking any sort of laws of reality. In The Screwy Truant, one gag has Screwy hitting Meathead over the head with everything he can find in a trunk labeled "Assorted Swell Stuff to Hit Dog on Head". When he finishes, Meathead remarks, "Gee whiz! He hit me with everything but the kitchen sink!" Screwy responds with, "Well, don't want to disappoint you, chum", then pulls out that very item and bashes him over the head with it.

Screwy would make his last regular appearance in the 1946 short Lonesome Lenny (a broad parody of the characters of George and Lenny from the John Steinbeck novel Of Mice and Men). In the cartoon, Screwy gets adopted from a pet store by a wealthy woman as a new companion for her pet Lenny, a large dimwitted dog with unfathomable strength. By the end of the cartoon, Lenny reveals that he accidentally "killed" Screwy by crushing him to death from a hug, with him lifting up the squirrel's flattened body from his "pocket" as evidence. However, Screwy suddenly opens one eye and brings a sign out from behind his back that reads, "Sad ending, isn't it?", implying he is still alive.

The reason as to why Screwy was discontinued after five cartoons was said to be that Tex Avery grew to openly dislike the character. Animator Mark Kausler used to send Avery letters about his rendition of Screwy, only for Avery to throw away anything related to the character.

Meathead Dog made a cameo appearance in the 1988 film Who Framed Roger Rabbit. He is seen sniffing around at R. K. Maroon's Cartoon Studio in the film's beginning. Screwy is mockingly mentioned by one of Eddie Valiant's bar patrons Angelo: "Who's your client, Mr. Detective of the Stars? Chilly Willy, or Screwy Squirrel?"

In 1993, Hanna-Barbera resurrected Screwy in new animation for the series Droopy, Master Detective as part of Fox Kids' programming block of Saturday morning cartoons. Those new cartoons featured the character's name as Screwball—never Screwy—and pitted him not against Meathead, but against a pair of typical Hanna-Barbera authority figures, a human park attendant named Dweeble and his oafish dog Rumply. "Screwball" himself wore a T-shirt and often a "Napoleon-style" bicorne hat.