The Screen Actors' Guild, the union which represents Hollywood actors, says its members will boycott next weekend's Golden Globe Awards in the US.
Actors' support for the protest will be solid, the union says
Union president Alan Rosenberg said there was "unanimous agreement" not to cross picket lines set up by writers who are on strike over royalties.
The Golden Globes, awarded to actors in television and film, are second in prestige only to the Oscars.
Without top actors present, TV networks may not bother to screen the event.
It is difficult to imagine a ceremony honouring excellence in film-making, without actors there to accept the awards, says the BBC's Peter Bowes in Los Angeles.
'Solidarity and support'
"After considerable outreach to Golden Globe actor nominees and their representatives over the past several weeks, there appears to be unanimous agreement that these actors will not cross WGA (Writers' Guild of America) picket lines," Mr Rosenberg said.
Late-night host David Letterman was off the air for two months
However, the Hollywood Foreign Press Association, which organises the Golden Globes, said it was continuing talks to find a compromise which would allow the event to take place "with the creative community present".
For its part, the WGA thanked the actors' union for its "solidarity and support".
The Writers' Guild of America has been on strike since early November.
Its members are in dispute over so-called "residuals" - royalties for work distributed online or released on DVD.
The WGA says it is engaged in a "crucial struggle that will protect our income and intellectual property rights for generations to come".
The dispute has virtually halted the production of TV comedy and drama shows.
However, talk shows resumed this week, with David Letterman's show reaching an "interim agreement" with WGA members.
Rival host Jay Leno is still subject to pickets, however.