Bugs Bunny is a cartoon character created in the late 1930s at Warner Bros. Cartoons (originally Leon Schlesinger Productions) and voiced originally by Mel Blanc. Bugs is best known for his featured roles in the Looney Tunes and Merrie Melodies series of animated short films, produced by Warner Bros. Early iterations of the character first appeared in Ben Hardaway's Porky's Hare Hunt (1938) and subsequent shorts before Bugs's definitive character traits debuted in Tex Avery's A Wild Hare (1940). Bob Givens, Chuck Jones, and Robert McKimson are credited for defining Bugs's visual design.

Bugs is an anthropomorphic gray-and-white rabbit or hare who is characterized by his flippant, insouciant personality, his Brooklyn accent, and his catchphrase "Eh... What's up, doc?". He is typically portrayed as a trickster, outwitting foes like Elmer Fudd and Yosemite Sam as well as various authority figures and criminals. He develops a friendly rivalry with Daffy Duck. Through his popularity during the golden age of American animation, Bugs became an American cultural icon and Warner Bros.' official mascot.

Bugs starred in more than 160 short films produced between 1940 and 1964. He has since appeared in feature films, television shows, comics, and other media. He has appeared in more films than any other cartoon character, is the ninth most-portrayed film personality in the world and has his own star on the Hollywood Walk of Fame.

According to Chase Craig, who wrote and drew the first Bugs Bunny comic Sunday pages and the first Bugs comic book, "Bugs was not the creation of any one man; however, he rather represented the creative talents of perhaps five or six directors and many cartoon writers including Charlie Thorson. In those days, the stories were often the work of a group who suggested various gags, bounced them around and finalized them in a joint story conference." A prototype Bugs rabbit with some of the personality of a finalized Bugs, though looking very different, was originally featured in the film Porky's Hare Hunt, released on April 30, 1938. It was co-directed by Ben "Bugs" Hardaway and an uncredited director Cal Dalton (who was responsible for the initial design of the rabbit). This cartoon has an almost identical plot to Avery's Porky's Duck Hunt (1937), which had introduced Daffy Duck. Porky Pig is again cast as a hunter tracking a silly prey who is more interested in driving his pursuer insane and less interested in escaping. Hare Hunt replaces the little black duck with a small white rabbit. According to Friz Freleng, Hardaway and Dalton had decided to "dress the duck in a rabbit suit". The white rabbit had an oval head and a shapeless body. In characterization, he was "a rural buffoon". Mel Blanc gave the character a voice and laugh much like those he later used for Woody Woodpecker. He was loud, zany with a goofy, guttural laugh. The rabbit character was popular enough with audiences that the Termite Terrace staff decided to use it again.

The rabbit comes back in Prest-O Change-O (1939), directed by Chuck Jones, where he is the pet rabbit of unseen character Sham-Fu the Magician. Two dogs, fleeing the local dogcatcher, enter the rabbit's absent master's house. The rabbit harasses them but is ultimately bested by the bigger of the two dogs. This version of the rabbit was cool, graceful, and controlled. He retained the guttural laugh but was otherwise silent.

The rabbit's third appearance comes in Hare-um Scare-um (1939), directed again by Dalton and Hardaway. This cartoon—the first in which he is depicted as a gray bunny instead of a white one—is also notable as the rabbit's first singing role. Charlie Thorson, lead animator on the film, gave the character a name. He had written "Bugs's Bunny" on the model sheet that he drew for Hardaway. In promotional material for the cartoon, including a surviving 1939 presskit, the name on the model sheet was altered to become the rabbit's own name: "Bugs" Bunny (quotation marks only used, on and off, until 1944).

In his autobiography, Blanc claimed that another proposed name for the character was "Happy Rabbit." In the actual cartoons and publicity, however, the name "Happy" only seems to have been used in reference to Bugs Hardaway. In Hare-um Scare-um, a newspaper headline reads, "Happy Hardaway." Animation historian David Gerstein disputed that "Happy Rabbit" was ever used as an official name, arguing that the only usage of the term came from Mel Blanc himself in humorous and fanciful tales he told about the character's development in the 1970s and 1980s; the name "Bugs Bunny" was used as early as August 1939, in the Motion Picture Herald, in a review for Hare-um Scare-um.

Thorson had been approached by Tedd Pierce, head of the story department, and asked to design a better look for the rabbit. The decision was influenced by Thorson's experience in designing hares. He had designed Max Hare in Toby Tortoise Returns (Disney, 1936). For Hardaway, Thorson created the model sheet previously mentioned, with six different rabbit poses. Thorson's model sheet is "a comic rendition of the stereotypical fuzzy bunny". He had a pear-shaped body with a protruding rear end. His face was flat and had large expressive eyes. He had an exaggerated long neck, gloved hands with three fingers, oversized feet, and a "smart aleck" grin. The result was influenced by Walt Disney Animation Studios' tendency to draw animals in the style of cute infants. He had an obvious Disney influence, but looked like an awkward merger of the lean and streamlined Max Hare from The Tortoise and the Hare (1935) and the round, soft bunnies from Little Hiawatha (1937).