In case you're not up on your movies, William Friedkin is basically a legend in the business.
As well as directing The French Connection, Sorcerer, To Live And Die In L.A., Friedkin directed the now-iconic horror classic The Exorcist. Friedkin was nominated for Best Director in 1973 for that film, but won two years prior for The French Connection. Per TVLine, Friedkin will voice a doctor in a segment of this year's Treehouse of Horror episode.
The segment, called Mmm... Homer, sees Homer eating himself after he's left alone in the house when Marge and the children leave. There's no word yet on how Friedkin's character factors into all of that, but the reason for Friedkin's inclusion probably has something to do with Ben Daniels, who currently stars in Fox's TV adaptation of The Exorcist, playing a role in another segment of this year's episode.
Brand synergy, people. Look it up.