“Fight Club” director David Fincher and “M*A*S*H” writer Larry Gelbart have a new comedy series in development at FX, sources said.

The untitled project is about a psychologist who becomes the flavor of the month among Hollywood celebrities due to his penchant for ruthless honesty. Mr. Fincher and Mr. Gelbart will executive produce.

If greenlighted, the project would be the first television series for Mr. Fincher, who scored critical and box office success with “Seven,” “Fight Club” and “Panic Room.” Mr. Fincher also has a small role portraying himself in the premiere episode of FX’s upcoming drama “Dirt.”

In addition to developing the movie “M*A*S*H” for television, Mr. Gelbart’s credits include his Academy Award-nominated screenplay for “Tootsie.” The proposed FX series would be his first television project since the 2003 HBO film “And Starring Pancho Villa as Himself.”

In a June 19 interview with TelevisionWeek, FX President and General Manager John Landgraf expressed doubt about the viability of scripted comedy on basic cable.

Still, he added, that doesn’t mean a network won’t formulate a fresh take on the genre and prove the conventional wisdom wrong. With the renewal of FX’s “It’s Always Sunny in Philadelphia” and the development of the Fincher/Gelbart project, Mr. Landgraf aims for FX to be the first cable network to break the scripted comedy jinx.

An FX spokesman declined on behalf of the network, Mr. Fincher and Mr. Gelbart to comment on the project.