Here it must be stressed that Bugs Bunny was not the creation of one man, but rather a character that developed over time. In fact, the genesis of Bug Bunny at least goes back to 1938 with the Porky Pig cartoon "Porky's Hare Hunt", which featured a hare who looked very different from Bugs, but did have some of his personality quirks. Other prototypes for Bugs Bunny would appear in the shorts "Prest-O Change-O" (1939) and "Hare-um Scare-um" (1939). "Hare-um Scare-um" (1939) is very significant in that the hare featured in the cartoon looks a lot like Bugs Bunny, although with a personality closer to the early Daffy Duck and a voice that was entirely different (complete with a Woody Woodpecker type laugh). A slight different version of this particular rabbit appeared in the Elmer Fudd short "Elmer's Candid Camera" (1940). In "Elmer's Candid Camera" the rabbit looks even more like Bugs, although he still has a completely different voice.
That brings us up to "A Wild Hare". "A Wild Hare" was directed by the legendary Tex Avery with animation by Virgil Ross, Robert McKimson, and Rod Scribner. "A Wild Hare" proved very successful, even earning a nomination for the Oscar for Best Short Subject (Cartoon). It lost to the MGM animated short "The Milky Way". By the way, the third nominee for Best Short Subject (Cartoon) was another historic cartoon, 'Puss Gets the Boot"--the very first cartoon featuring Tom and Jerry (although Tom is called "Jasper" throughout the short). Regardless, the success of "A Wild Hare" would guarantee Bugs Bunny a place in Warner Bros.' stable of characters. He would go onto become one of the most popular animated characters of all time, if not the most popular.
For those who would like to see "A Wild Hare", here it is, courtesy of DailyMotion.
Merrie Melodies - A Wild Hare (1940) by Cartoonzof2006