New York Times theater critic Charles Isherwood was recently fired over his cozy relationship with uber-producer Scott Rudin, sources tell Page Six.

After Isherwood clashed with Times chief theater critic Ben Brantley and assignment editors, execs at the Gray Lady combed through Isherwood’s emails and discovered a barrage of bitchy dialogue between him and Rudin, the producer of hits including “The Book of Mormon” and the revival of “Fences” starring Denzel Washington.

One source said there were years of tension between Isherwood and Brantley because Brantley would always get the plum shows to review. The source said, “The tension built up between Charles and Ben. Charles also had issues with his editors about his assignments. It got ugly when Charles complained Ben always reviewed the big shows and he never got a shot at them.

“Times executives combed through Charles’ ­emails and found numerous messages between him and Scott Rudin, where Isherwood said negative things about Brantley, and complained about his assignments and complained about editors at the paper.”

The source added that more emails along the same lines were discovered between Isherwood, who worked at the paper for 12 years, and Robyn Goodman, who’s produced shows including “In the Heights” and “Avenue Q.”

The source added, “The Times argued that those emails showed he had a too-cozy relationship with Rudin and Goodman, and they used it as grounds to fire him.” Isherwood, we’re told, is in arbitration with the paper and is going after the Times for wrongful dismissal.

Another source added, “He is a well-respected critic. It is natural that he would have a relationship with Rudin. It didn’t affect his reviews because Charles didn’t review Rudin’s shows — Ben always got them. Some people feel they used the emails as an excuse to get rid of him because his clashes made him unpopular in the office.”

Isherwood declined numerous requests to comment for this story. The Times said, “We don’t comment on personnel matters.”