Chef, as his nickname implies, was a school cafeteria cook at the South Park Elementary School. He was usually the only adult that the main characters on the show (Stan Marsh, Kyle Broflovski, Eric Cartman and Kenny McCormick) consistently asked for advice. A typical introduction went as such:Chef: Hello there, children!
Kids (in unison): Hey Chef.
Chef: How's it going?
One or all of kids: Bad.
Chef: Why bad?
One of the children then explained to him their problem. Chef used the word "children" often, even for the singular (for example, he referred to Eric Cartman as "children" in "Cartman's Mom Is a Dirty Slut," Stan Marsh as "children" in "Kenny Dies," and Butters Stotch as "children" in "Simpsons Already Did It"). He also tended to use "fudge" as a euphemism, particularly in early episodes.
While most of the inhabitants of South Park are white, Chef was one of the very few residents in town who was black; in fact the only other black people to consistently live in South Park are Token and his parents, who are not prominent characters until the fourth season. As a result, Chef (usually goodnaturedly, though not always) referred to most people in town with the racial slur "crackas," including the children.
Aside from cooking, Chef was passionate about singing - he wrote the song "Stinky Britches" which was later covered by Alanis Morissette - and "making sweet love down by the fire". He was based on such 1970s African-American singers as Isaac Hayes (who voiced him) and Barry White. Often, he agreed to give the boys advice in the form of songs, but winded up singing about having sex. Over time, however, like many earlier characters on the show, his role diminished, and in later seasons he did not sing much even when he did appear.
Despite his preoccupations with women and sex, Chef was generally one of the few level-headed adults in South Park. In addition to dispensing advice to "the children", Chef spoke out against outrageous ideas, and helped save South Park/the world in general from several disasters. However, Chef was not above performing nonsensical acts, such as buying a fancy TV that he couldn't even program (and that eventually turned into a combat robot).
In earlier seasons, Chef was often approached by the children when they were unfamiliar with a sexual term or practice. This happened so often that it got on Chef's nerves, several times he would say things like "Goddammit, children, why do I always have to be the one to teach you these things?", but go on to explain to them whatever they wanted to know anyway.
Chef’s last name suggests he could be at least partially of some Celtic descent, and indeed his parents live in Edinburgh, Scotland.
In the episode "Chef Goes Nanners" he briefly converted to Islam and adopted the name Abdul Mohammed Jabar Rauf Kareem Ali
In the episode "The Return of Chef" he died after joining the Super Adventure Club, but was later resurrected in that same episode as Darth Chef. He has not (to date) re-appeared after that episode.