Late-night shows are back, and so are its guests. But don't expect actors to talk about their movies or TV projects.

SAG members are forbidden from promoting projects, such as movies or TV shows, that are the subject of the strikes.

Actor Matthew McConaughey talks with Jimmy Fallon in an appearance on
Matthew McConaughey is joining The Tonight Show Starring Jimmy Fallon on Monday night. (Andrew Lipovsky/NBC via Getty Images)
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Matthew McConaughey will be the first guest on The Tonight Show Starring Jimmy Fallon on Monday when it returns to the air for the first time since the end of the months-long Hollywood writers strike that caused all late-night television shows to go dark. Just don't expect him to talk about his upcoming acting projects.

That's because McConaughey is a member of the Screen Actors Guild (SAG), which joined the Writers Guild of America writers by going on strike in July. SAG has yet to reach its own agreement with American Motion Picture and Television Producers (AMPTP), which represents Hollywood's studios and production companies like Netflix, Disney, NBCUniversal and Paramount Global.

Why can't he talk about his work?

SAG has very strict rules about what its members can or cannot say while they're striking.

Specifically, actors are forbidden from promoting projects such as movies or television shows that are the subject of the strikes, as well as taking part in promotional appearances like premieres, festivals, award shows — and late-night talk shows.

In this case, McConaughey will be appearing on The Tonight Show to promote his recently-released children’s book, Just Because, and not, say, his rumored participation in a Yellowstone spin-off.

Late-night writers were allowed to return to work on Wednesday after the Writers Guild of America reached a tentative agreement on a three-year contract with AMPTP.

What do the striking actors want?

Pretty much the same thing the writers did: Better pay and job security amid a streaming boom that has transformed the industry. SAG-AFTRA and AMPTP resumed talks Monday — just eight days after the writers guild reached its own deal.

"To be clear, this strike happened for good reasons," John Oliver said on Sunday's Last Week Tonight on HBO, the first late-night show to return with new episodes.

"Our industry has seen its workers severely squeezed in recent years. So, the Writers Guild went to strike and thankfully won. But, it took a lot of sacrifices from a lot of people to achieve that," Oliver explained, adding: "I am also furious that it took the studios 148 days to achieve a deal they could have offered on day f***ing one."

Who's on tonight?

The Tonight Show Starring Jimmy Fallon airs on NBC at 11:35 p.m. ET

  • Guests: Matthew McConaughey, John Mayer

The Late Show With Stephen Colbert airs on CBS at 11:35 p.m. ET

  • Guests: Neil deGrasse Tyson, Louis Cato

Late Night With Seth Meyers airs on NBC at 12:35 a.m. ET

  • Guests: None

Jimmy Kimmel Live! airs on ABC at 12 a.m. ET

  • Guests: Ar​​nold Schwarzenegger, Jason Isbell and the 400 Unit