Talk about hitting a guy when he’s down!

David S. Rosenthal, a former executive producer on “Spin City,” is publicly trashing series star Michael J. Fox, who quit the show to help find a cure for the Parkinson’s disease that afflicts him.

Rosenthal has dubbed Fox “a great pretender” and a control freak who threw “hissy fits” when demanding script rewrites.

“The problem is he’s such an egomaniac that he was not willing to hear from us and was just an abusive, horrible boss,” fumed Rosenthal, who was once fired from the TV show “Ellen.”

He went so far as to claim “nobody liked” Fox on the set of the hit ABC sitcom.

But a former “Spin City” cast member told us: “Michael J. Fox is one of the most thoughtful and considerate persons I’ve ever worked with.

“He was under tremendous pressure, yet always showed great concern for everyone.”

So, David S. — pick on somebody your own size!