Dean was born on January 24, 1979 to John and Mary Winchester in Lawrence, Kansas. He is the couples first child, four years older than his younger brother Sam. He is named after his maternal grandmother, Deanna Campbell.

When he was only four years old on November 2, 1983, his mother Mary was killed in Sam's nursery by the demon Azazel. Infant Sam is saved from the ensuing fire when his father takes him out of his crib and gives him to four year old Dean, who then carries him outside while their father unsuccessfully tries to rescue their mother.

After that night Dean felt responsible for Sam, and was always given the job to take care of him while they were growing up. Dean's father John raised him and Sam as Hunters of the supernatural. During Dean's childhood John would be away "hunting" a week or two at a time, so Dean had to partly raise Sam.

Dean appears to be a fan of Jack Nicholson, and possibly watches Oprah. He tends to make light of some of his and Sam's adventures, and is known to use crude humor and make sexual innuendos. Despite being in excellent physical shape, Dean is known to have very bad eating habits. He is often shown enjoying greasy, fattening, or otherwise unhealthy food, especially cheeseburgers; this is in stark contrast to Sam, who often favors a healthier diet and usually expresses either amazement or disgust at the food Dean eats. Dean is terrified of flying, and claims that it is the reason why he drives everywhere.

(Source: Wikipedia)