Executive Producer
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The executive producer is essentially the head of the show. The executive producer receives first billing in the closing credits; this began during season 5. Their main duties include setting the direction for the season, and takes care of the administrative side of producing a show as well.
Below is a list of executive producers and seasons they produced
Matt Groening, James L. Brooks and Sam Simon seasons 1, 2
Al Jean seasons 3, 4, 13, 14, 15, 16, 17, 18
Mike Reiss seasons 3, 4
David Mirkin seasons 5, 6
Bill Oakley seasons 7, 8
Josh Weinstein 7, 8
Mike Scully 9, 10, 11, 12,