Ryan Reynolds, Mandy Moore and Melissa Gilbert called out the Screen Actors Guild-American Federation of Television and Radio Artists (SAG-AFTRA) after the union issued new Halloween costume rules for striking actors.

On Wednesday, SAG-AFTRA posted a flyer with guidelines for observing the holiday without undermining the ongoing strike, which hit its 100th day Friday. The union instructed members to avoid dressing up as characters from struck content and instead opt for "generalized characters and figures (ghost, zombie, spider.)"

SAG-AFTRA also demanded its members refrain from posting "costumes from struck content on social media." The guidelines prohibit members from choosing some of the year's most popular costume choices, including Barbie, Wednesday Addams and Spider-Man.

The backlash to SAG-AFTRA's "strike-friendly" costume rules was swift with celebrities taking to social media to vent their frustration.

ACTORS' UNION SAG-AFTRA OFFERS ‘STRIKE-FRIENDLY’ TIPS FOR HALLOWEEN COSTUMES

ryan reynolds mandy moore

Ryan Reynolds, Mandy Moore and Melissa Gilbert are speaking out against SAG-AFTRA's strict Halloween costume rules.  (Getty)

"Is this a joke? Come on @sagaftra. This is what’s important? We’re asking you to negotiate in good faith on our behalf," Moore, 39, wrote on her Instagram story.

The "This Is Us" alum continued, "So many folks across every aspect of this industry have been sacrificing mightily for months. Get back to the table and get a fair deal so everyone can get back to work."

Reynolds, 46, mocked the union on X, formerly Twitter, joking about reprimanding his daughter James over her Halloween costume.

mandy moore instagram post about stike halloween costumes

Moore expressed her indignation in a post she shared on Instagram.  (Mandy Moore Instagram)

"I look forward to screaming 'scab' at my 8 year old all night," the "Deadpool" actor wrote Thursday, referring to the derogatory term for a union member who breaks strike rules or crosses picket lines.

"She’s not in the union but she needs to learn," he added. 

After Reynolds' tweet, SAG-AFTRA issued a statement clarifying that the rules do not apply to members' children.

mandy moore on picket line

The union's Halloween guidelines prohibit members from dressing up as characters from struck content. (Kevin Winter/Getty Images)

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"SAG-AFTRA issued Halloween guidance in response to questions from content creators and members about how to support the strike during this festive season. This was meant to help them avoid promoting struck work, and it is the latest in a series of guidelines we have issued. It does not apply to anyone’s kids," the union wrote, according to The Hollywood Reporter.

"We are on strike for important reasons, and have been for nearly 100 days. Our number one priority remains getting the studios back to the negotiating table so we can get a fair deal for our members, and finally put our industry back to work."

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Gilbert, who served as the president of SAG-AFTRA from 2001 to 2005, blasted the union in a scathing Instagram post Thursday.

"THIS is what you guys come up with?," the 59-year-old "Little House on the Prairie" actress wrote.

melissa gilbert strike

Gilbert, who served as the president of SAG-AFTRA from 2001 to 2005, blasted the union in a scathing Instagram post Thursday. (Gotham/GC Images)

"Literally no one cares what anyone wears for Halloween. I mean, do you really think this kind of infantile stuff is going to end the strike? We look like a joke. Please tell me you’re going to make this rule go away….and go negotiate!"

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"For the love of God, people are suffering mightily and this is what you have to say…c’mon guys….@officialfrandrescher @duncanci," Gilbert added, tagging the Instagram accounts of current SAG-AFTRA President Fran Drescher and chief negotiator Duncan Crabtree-Ireland.

The "Dancing WIth The Stars" alum also reposted a caption from an Instagram update by Canadian actor Kevin Zegers that said, "This is the kind of silly bulls--- that keeps us on strike."

"‘Let’s enact a policy that makes us look petty and incompetent at the same time’ @officialfrandrescher."