There's a neat interview with animation legend Ralph Bakshi here .
If you ask me, without Ralph Bakshi's feature films, we would not have the Simpsons, South Park, Robert Zemekis'es creepy mo-cap flicks or even the Don Bluth film catalog .
Periodically, there's a push to formally recognize animation as an artistically legitimate film venue, usually though handling themes unexplored in the medium or through "adult content. But inevitably, public perception seems to swing back to the "children's entertainment" profiling, animation listed as a "genre" on IMDB and so forth.
Bakshi's profile, career info and influence can be summed up better at his official website or even just his wikipedia entry so I won't burn up more page space here, just check out the interview.