A Broadway actress has taken the rare step of publicly challenging the tone of anonymous online comment boards where theater lovers exchange news, gossip and opinions, often with a heavy dose of snark.

Patti Murin, who was to star in a Broadway musical called “Nerds” this spring, on Thursday posted a lengthy cri de coeur objecting to some of the comments on a chat board run by BroadwayWorld in the hours after the show, about Steve Jobs and Bill Gates, was canceled. One commenter said of an actor, “I hope he’s not playing either Jobs or Gates because neither of them are mentally retarded.” Another described the show, which had not yet begun previews (although it had been staged elsewhere in previous years) as “terrible,” and yet another said that Ms. Murin was not capable of hitting a high C (which Ms. Murin denies in colorful language that cannot be reprinted here).

Ms. Murin, who starred in the Broadway production of “Lysistrata Jones,” wrote that she appreciated the role chat boards play in allowing theater fans to talk to one another, but objected to what she called “a cesspool of ignorance and negativity”:

But then there’s also a nasty faction of “fans” who take our hard work and turn it into gossip, and pissing contests over who can come up with the snarkiest insult or meme or GIF, and bragging rights over who is the most insider-y when it comes to Broadway and theater secrets. It’s snarky. And you know, I like some light snark. But it’s nasty snark. Immature and uninformed people are hiding behind screen names and posting incorrect information, passing on rumors as facts.

The theater community is small, and the BroadwayWorld chat board, which has had six million messages since it was started in 2003, claims to be the largest for theater fans. The website, which is independently owned by its founder, Robert Diamond, has news, features and listings about theater in multiple cities. Mr. Diamond said that the chat board participants are “a wide variety of people that range from Tony-winning performers to 14-year-olds in Kansas City,” and said the forum was established to “create a place for those of us that didn’t grow up with theater-loving friends to chat about the things we were obsessing about.”