4-Layer-Deep Acting

1-layer-deep acting is an actor acting as a character.

2-layer-deep acting is an actor acting as a character who is also acting as a character. Examples:

Movies with characters who are actors in-universe. In Once Upon a Time in Hollywood, Leonardo DiCaprio plays the actor Rick Dalton. In some scenes, we can see Rick Dalton shooting a movie, playing the antagonist in a Western. In those moments we see Leonardo DiCaprio doing 2-layer-deep acting.
Movies where someone is disguised as someone else. In Mission: Impossible – Fallout, Tom Cruise plays the spy Ethan Hunt. In one scene, Ethan Hunt has to assume the identity of bad guy John Lark and act like him to infiltrate a meeting, 2-layer-deep acting again. Another from the same movie: spy Benji uses a high-tech mask to take the place of bad guy Lane. In that scene, actor Sean Harris (who plays Lane) must act as the character of Benji acting as his character Lane.

I find these situations interesting because the real-life actor has to operate at two layers simultaneously. Especially if the in-universe “acting” is supposed to be imperfect, the real actor might have to show their character making acting mistakes while playing their character, without breaking the immersion at the first layer. They have to perfectly act out imperfect acting.

What’s the maximum depth you’ve seen this pattern go?

Immortality

Major spoilers for the game Immortality after this point, and these are spoilers you really don't want to see if you're planning on playing the game.

Immortality involves watching live-action clips from several movies and their behind-the-scenes footage to figure out the mystery of what happened to in-universe actress Marissa Marcel. Real-life actress Manon Gage plays Marissa Marcel (layer 1).

One of Marissa Marcel’s movies is called Two of Everything, where Marcel plays both popstar Maria and her body double Heather. These characters are normally both at layer 2.

At several points in the movie, Maria asks Heather to take her place at events she doesn’t want to do herself. So Heather, acting as Maria, goes to perform at a billionaire’s birthday party instead of her. Layer 3.

As if that was not enough, through secret scenes we can access in the game, we find out that Marissa Marcel is not a human actress in the first place. Instead she is an immortal being called “The One”, who takes on the forms of humans and lives their lives. Layer 4 (or perhaps, the real Layer 1)!

Is that not a little crazy? We are watching real-life actress Manon Gage, acting as an immortal being called The One, acting as a human called Marissa Marcel, acting as a movie character called Heather, acting as another character in that movie called Maria.

I wonder how it was like to keep all this in mind during the scenes, trying to let a little bit of the upper layers pass through even though you’re probably focusing on the last 2 layers or so at any given time.

Passages from the book IMMORTALITY: Design Works show the cast were definitely thinking about this:

As with the other actors, Donahue spent time discussing Immortality's extra layer of fiction with Barlow. After all, everyone was effectively playing a dual role — more in Gage's case, and the other characters who are inhabited by The One and The Other.

It’s really fun revisiting scenes from Immortality to analyze them from this perspective!