Garfield’s creator, Jim Davis, was born to Indiana farmers who raised cows and feed crops for cows, along with a passel of 25 cats. Bouts with asthma as a child led Davis's mother to encourage him to draw, something he could do without exerting himself. After college, Davis worked in advertising until he apprenticed with "Tumbleweeds" cartoonist Tom K. Ryan. His first effort was called "Gnorm Gnat," but a comics editor told him that people couldn't relate to bugs. Davis looked at other successful comics and realized that people do like dogs like Snoopy and Marmaduke. Why not cats?
im Davis's first Garfield comic strip debuted on June 19, 1978 in 41 newspapers. The antics of a cranky, overweight orange cat quickly drew fans. When a Chicago paper dropped the strip in favor of something else, more than 1,000 readers complained until they reinstated it. The look of the comic strip has changed over the years, but Davis has said that he based his simplicity of line on Charles Schulz's work in "Peanuts."
Jim Davis said of Garfield, "If he were a human, he'd be despicable" [Source: Jim Davis interview]. Garfield is cranky, lazy and the pinnacle of bad health. His running commentary on Jon Arbuckle's pathetic love life plays on the stereotype of the lonely cat lady -- only this time it's a wimpy guy who can't get his cat under control, much less arrange a successful date. The comic strip also cements the dog/cat dichotomy, with Odie as the happy, dumb, slobbery dog and Garfield as the largely independent, condescending lord of the manor.
Part of the comic strip's success may be that it's so apolitical. It talks about loving food and naps and hating work and Mondays. It's the exact opposite of a New Yorker cartoon. Anyone of any age can appreciate it, and it isn't too politically correct or concerned with lofty ideas. In an age where the Cookie Monster has to start playing down cookies, Garfield remains unrepentant in his food joy (much to Jon's chagrin).
According to wikipedia